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Erlang Run-Time System Application (ERTS)
Release Notes
Version 5.9.1

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- ERTS Release Notes
  - Top of chapter
  - Erts 5.9.1
  - Erts 5.9.0.1
  - Erts 5.9
  - Erts 5.8.5
  - Erts 5.8.4
  - Erts 5.8.3.2
  - Erts 5.8.3.1
  - Erts 5.8.3
  - Erts 5.8.2
  - Erts 5.8.1.2
  - Erts 5.8.1.1
  - Erts 5.8.1
  - Erts 5.8
  - Erts 5.7.5.2
  - Erts 5.7.5.1
  - Erts 5.7.5
  - Erts 5.7.4
  - Erts 5.7.3
  - Erts 5.7.2
  - Erts 5.7.1
  - Erts 5.7
  - Erts 5.6.5.1
  - Erts 5.6.5
  - Erts 5.6.4.2
  - Erts 5.6.4.1
  - Erts 5.6.4
  - Erts 5.6.3.3
  - Erts 5.6.3.2
  - Erts 5.6.3.1
  - Erts 5.6.3
  - Erts 5.6.2
  - Erts 5.6.1.1
  - Erts 5.6.1
  - Erts 5.6
  - Erts 5.5.5.5
  - Erts 5.5.5.4
  - Erts 5.5.5.3
  - Erts 5.5.5.2
  - Erts 5.5.5.1
  - Erts 5.5.5
  - Erts 5.5.4.3
  - Erts 5.5.4.2
  - Erts 5.5.4.1
  - Erts 5.5.4
  - Erts 5.5.3.1
  - Erts 5.5.3
  - Erts 5.5.2.2
  - Erts 5.5.2.1
  - Erts 5.5.2
  - Erts 5.5.1.1
  - Erts 5.5.1
  - ERTS 5.5
  - ERTS 5.4.13
  - ERTS 5.4.12
  - ERTS 5.4.11
  - ERTS 5.4.10
  - ERTS 5.4.9.2
  - ERTS 5.4.9.1
  - ERTS 5.4.9
  - ERTS 5.4.8
  - ERTS 5.4.7
  - ERTS 5.4.6
  - ERTS 5.4.5
  - ERTS 5.4.4
  - ERTS 5.4.3
  - ERTS 5.4.2.1
  - ERTS 5.4.2
  - ERTS 5.4.1

# 1 ERTS Release Notes

This document describes the changes made to the ERTS application.

### 1.1 Erts 5.9.1

#### Fixed Bugs and Malfunctions

- erlang:system_profile errorneous profiled the profiler process when observing runnable processes. This has been corrected.

  Own Id: OTP-9849

- Calling trace_info/2 asking for information about a function that had native could could crash the run-time system.

  Own Id: OTP-9886

- reduce smp locking time range in erts_garbage_collect (thanks to Jovi Zhang)

  Own Id: OTP-9912

- Fix typo in supervisor behaviour doc (Thanks to Ricardo Catalinas Jiménez)

  Own Id: OTP-9924

- Correct spelling of registered (Thanks to Richard Carlsson)

  Own Id: OTP-9925

- erts: Remove unused variable (Thanks to Jovi Zhang)

  Own Id: OTP-9926

- Fix bug in ETS with compressed option and insertion of term containing large integers (>2G) on 64-bit machines. Seen to cause emulator crash. (Thanks to Diego Llarrull for excellent bug report)

  Own Id: OTP-9932

- Handle Linux OS where /sys/devices/system/node is only readable by root. Fallback to /sys/devices/system/cpu for topology info.

  Own Id: OTP-9978

- When an escript ends now all printout to standard output and standard error gets out on the terminal. This bug has been corrected by changing the behaviour of erlang:halt/0,1, which should fix the same problem for other escript-like applications, i.e that data stored in the output port driver buffers got lost when printing on a TTY and exiting through erlang:halt/0,1.

  The BIF:s erlang:halt/0,1 has gotten improved semantics and there is a new BIF erlang:halt/2 to accomplish something like the old semantics. See the documentation.

  Now erlang:halt/0 and erlang:halt/1 with an integer argument will close all ports and allow all pending async threads operations to finish before exiting the emulator. Previously erlang:halt/0 and erlang:halt(0) would just wait for pending async threads operations but not close ports. And erlang:halt/1 with a non-zero integer argument would not even wait for pending async threads operations.

  To roughly the old behaviour, to not wait for ports and async threads operations when you exit the emulator, you use erlang:halt/2 with an integer first argument and an option list containing {flush,false} as the second argument. Note that now is flushing not dependant of the exit code, and you can not only flush async threads operations which we deemed as a strange behaviour anyway.

  Also, erlang:halt/1,2 has gotten a new feature: If the first argument is the atom 'abort' the emulator is aborted producing a core dump, if the operating system so allows.

  Own Id: OTP-9985

- Added check to inet driver to avoid building on operating systems that do not yet have IPv6 compatible socket API. (Thanks to Peer Stritzinger)

  Own Id: OTP-9996

- Fix bug when the number of CPUs actually found is lower than the configured value. (Thanks to Benjamin Herrenschmidt)

  Own Id: OTP-10004

- The runtime system without SMP support and without thread support erroneously busy waited when no work was present. This bug first appeared in erts-5.9.

  Own Id: OTP-10019

- Various typographical errors corrected in documentation for common_test, driver, erl_driver and windows installation instructions. (Thanks to Tuncer Ayaz)

  Own Id: OTP-10037

- Fix memory leak caused by race on exiting process

  Own Id: OTP-10041

#### Improvements and New Features

- Add erlang:statistics(scheduler_wall_time) to ensure correct determination of scheduler utilization. Measuring scheduler utilization is strongly preferred over CPU utilization, since CPU utilization gives very poor indications of actual scheduler/vm usage.

  Own Id: OTP-9858

- ERTS internal API improvements. In some cases the amount of atomic read operations needed have been reduced due to this.

  Own Id: OTP-9922

- The DTrace source patch from Scott Lystig Fritchie is integrated in the source tree. Using an emulator with dtrace probe is still not supported for production use, but may be a valuable debugging tool. Configure with --with-dynamic-trace=dtrace (or --with-dynamic-trace=systemtap) to create a build with dtrace probes enabled. See runtime_tools for documentation and examples.

  Own Id: OTP-10017

#### Known Bugs and Problems

- enif_make_copy may invalidate enif_inspect_binary.

  Own Id: OTP-9828

### 1.2 Erts 5.9.0.1

#### Fixed Bugs and Malfunctions

- A feature test for the lwsync instruction performed on PowerPC hardware at runtime system startup got into an eternal loop if the instruction was not supported. This bug was introduced in erts-5.9/OTP-R15B.

  Own Id: OTP-9843

- I/O events could potentially be delayed for ever when enabling kernel-poll on a non-SMP runtime system executing on Solaris. When also combined with async-threads the runtime system hung before completing the boot phase. This bug was introduced in erts-5.9/OTP-R15B.

  Own Id: OTP-9844

### 1.3 Erts 5.9

#### Fixed Bugs and Malfunctions

- Honor option packet_size for http packet parsing by both TCP socket and erlang:decode_packet. This gives the ability to accept HTTP headers larger than the default setting, but also avoid DoS attacks by accepting lines only up to whatever length you wish to allow. For consistency, packet type line also honor option packet_size. (Thanks to Steve Vinoski)

  Own Id: OTP-9389

- A few contracts in the lists module have been corrected.

  Own Id: OTP-9616

- The Unicode noncharacter code points 16#FFFE and 16#FFFE were not allowed to be encoded or decoded using the unicode module or bit syntax. That was inconsistent with the other noncharacters 16#FDD0 to 16#FDEF that could be encoded/decoded. To resolve the inconsistency, 16#FFFE and 16#FFFE can now be encoded and decoded. (Thanks to Alisdair Sullivan.)

  *** POTENTIAL INCOMPATIBILITY ***

  Own Id: OTP-9624

- Make epp search directory of current file first when including another file This completes a partial fix in R11 that only worked for include_lib(). (Thanks to Richard Carlsson)

  Own Id: OTP-9645

- Fixed memory leak in enif_inspect_io_list_as_binary when applied on a process independent environment.

  Own Id: OTP-9668

- The number of beam catches allowed in code are no longer statically defined and will grow according to its need.

  Own Id: OTP-9692

- Add missing parenthesis in heart doc.

  Add missing spaces in the Reference Manual distributed section.

  In the HTML version of the doc those spaces are necessary to separate those words.

  Own Id: OTP-9693

- Fixes module erlang doc style: option description (Thanks to Ricardo Catalinas Jiménez)

  Own Id: OTP-9697

- Specifying a scope to binary:match/3 when using multiple searchstrings resulted in faulty return values. This is now corrected.

  Own Id: OTP-9701

- The runtime system crashed if more than one thread tried to exit the runtime system at the same time.

  Own Id: OTP-9705

- Fix documentation for erlang:process_flag/2

  For the subsection about process_flag(save_calls, N) there's an unrelated paragraph about process priorities which was copied from the preceeding subsection regarding process_flag(priority, Level). (Thanks to Filipe David Manana)

  Own Id: OTP-9714

- Calls to erlang:system_flag(schedulers_online, N) and/or erlang:system_flag(multi_scheduling, block|unblock) could cause internal data used by this functionality to get into an inconsistent state. When this happened various problems occurred. This bug was quite hard to trigger, so hopefully no-one has been effected by it.

  A spinlock used by the run-queue management sometimes got heavily contended. This code has now been rewritten, and the spinlock has been removed.

  Own Id: OTP-9727

- Use libdlpi to get physical address (Thanks to Trond Norbye)

  Own Id: OTP-9818

#### Improvements and New Features

- An option list argument can now be passed to file:read_file_info/2, file:read_link_info/2 and file:write_file_info/3 and set time type information in the call. Valid options are {time, local}, {time, universal} and {time, posix}. In the case of posix time no conversions are made which makes the operation a bit faster.

  Own Id: OTP-7687

- A number of memory allocation optimizations have been implemented. Most optimizations reduce contention caused by synchronization between threads during allocation and deallocation of memory. Most notably:

  - Synchronization of memory management in scheduler specific allocator instances has been rewritten to use lock-free synchronization.
  - Synchronization of memory management in scheduler specific pre-allocators has been rewritten to use lock-free synchronization.
  - The 'mseg_alloc' memory segment allocator now use scheduler specific instances instead of one instance. Apart from reducing contention this also ensures that memory allocators always create memory segments on the local NUMA node on a NUMA system.

  Own Id: OTP-7775

- The ethread atomic memory operations API used by the runtime system has been extended and improved.

  The ethread library now also performs runtime tests for presence of hardware features, such as for example SSE2 instructions, instead of requiring this to be determined at compile time.

  All uses of the old deprecated atomic API in the runtime system have been replaced with the use of the new atomic API. In a lot of places this change imply a relaxation of memory barriers used.

  Own Id: OTP-9014

- gen_sctp:open/0-2 may now return {error,eprotonosupport} if SCTP is not supported

  gen_sctp:peeloff/1 has been implemented and creates a one-to-one socket which also are supported now

  *** POTENTIAL INCOMPATIBILITY ***

  Own Id: OTP-9239

- Sendfile has been added to the file module's API. sendfile/2 is used to read data from a file and send it to a tcp socket using a zero copying mechanism if available on that OS.

  Thanks to Tuncer Ayaz and Steve Vinovski for original implementation

  Own Id: OTP-9240

- enif_get_reverse_list function added to nif API. This function should be used to reverse small lists which are deep within other structures making it impractical to do the reverse in Erlang.

  Own Id: OTP-9392

- The deprecated concat_binary/1 BIF has been removed. Use list_to_binary or iolist_to_binary/1 instead.

  *** POTENTIAL INCOMPATIBILITY ***

  Own Id: OTP-9421

- Erlang/OTP can now be built using parallel make if you limit the number of jobs, for instance using 'make -j6' or 'make -j10'. 'make -j' does not work at the moment because of some missing dependencies.

  Own Id: OTP-9451

- Line number and filename information are now included in exception backtraces as a fourth element in the MFA tuple. The information will be pretty-printed by the shell and used by common_test to provide better indication of where a test case.

  *** POTENTIAL INCOMPATIBILITY ***

  Own Id: OTP-9468

- All binary constants used to be handled as heap binaries (i.e. the entire binary would be copied when sent to another process). Binary constants larger than 64 bytes are now refc binaries (i.e. the actual data in the binary will not be copied when sent to another process).

  Own Id: OTP-9486

- If a float and an integer is compared, the integer is only converted to a float if the float datatype can contain it. Otherwise the float is converted to an integer.

  *** POTENTIAL INCOMPATIBILITY ***

  Own Id: OTP-9497

- Add NIF function enif_is_number

  This function allows for easily determining if a term represents or not a number (integer, float, small or big).(Thanks to Filipe David Manana)

  Own Id: OTP-9629

- The ERTS internal system block functionality has been replaced by new functionality for blocking the system. The old system block functionality had contention issues and complexity issues. The new functionality piggy-backs on thread progress tracking functionality needed by newly introduced lock-free synchronization in the runtime system. When the functionality for blocking the system isn't used, there is more or less no overhead at all. This since the functionality for tracking thread progress is there and needed anyway.

  Own Id: OTP-9631

- An ERTS internal, generic, many to one, lock-free queue for communication between threads has been introduced. The many to one scenario is very common in ERTS, so it can be used in a lot of places in the future. Currently it is used by scheduling of certain jobs, and the async thread pool, but more uses are planned for the future.

  Drivers using the driver_async functionality are not automatically locked to the system anymore, and can be unloaded as any dynamically linked in driver.

  Scheduling of ready async jobs is now also interleaved in between other jobs. Previously all ready async jobs were performed at once.

  Own Id: OTP-9632

- Tuple funs (a two-element tuple with a module name and a function) are now officially deprecated and will be removed in R16. Use 'fun M:F/A' instead. To make you aware that your system uses tuple funs, the very first time a tuple fun is applied, a warning will be sent to the error logger.

  Own Id: OTP-9649

- Changed the internal BIF calling convention. Will make simpler faster code and allow BIFs with an arbitrary arity.

  Own Id: OTP-9662

- Windows native critical sections are now used internally in the runtime system on Windows as mutex implementation. This since they perform better under extreme contention than our own implementation.

  Own Id: OTP-9671

- Convert some erl_nif macros into inline functions. Allow for better compile time type checking. (Thanks to Tuncer Ayaz)

  Own Id: OTP-9675

- The +scl command line flag has been added. It can be used for disabling compaction of scheduler load. For more information see the erl(1) documentation.

  Own Id: OTP-9695

- The build system has been updated so that Erlang/OTP can be built on Mac OS X Lion systems without a GCC compiler. The INSTALL guide has been updated with instructions on how to install a GCC compiler and build Erlang/OTP with it, in order to get a run-time system with better performance.

  Own Id: OTP-9712

- When loading a module, the system use to run on a single scheduler during the entire loading process. This has been changed to only take down the system just before inserting the loaded code into the system tables, resulting in a much shorter disruption if a module is loaded in a busy system. (Suggested by Bob Ippolito.)

  Own Id: OTP-9720

- Possible to run HiPE without floating point exceptions (FPE). Useful on platforms that lack reliable FPE. Slower float operations compared to HiPE with FPE.

  Own Id: OTP-9724

- As of ERTS version 5.9 (OTP-R15B) the runtime system will by default not bind schedulers to logical processors.

  If the Erlang runtime system is the only operating system process that binds threads to logical processors, this improves the performance of the runtime system. However, if other operating system processes (as for example another Erlang runtime system) also bind threads to logical processors, there might be a performance penalty instead. In some cases this performance penalty might be severe. Due to this, we change the default so that the user must make an active decision in order to bind schedulers.

  *** POTENTIAL INCOMPATIBILITY ***

  Own Id: OTP-9726

- The use of erlang:system_flag(scheduler_bind_type, _) and erlang:system_flag(cpu_topology, _) have been deprecated and scheduled for removal in erts-5.10/OTP-R16. For more information see the documentation of erlang:system_flag/2.

  *** POTENTIAL INCOMPATIBILITY ***

  Own Id: OTP-9749

- An ancient workaround for a Windows bug was removed from the open_port code, open_port({spawn,...}...) is now faster. Thanks to Daniel Goertzen.

  Own Id: OTP-9766

- The use of deprecated 32bit time_t on 32bit Windows is removed.

  Own Id: OTP-9767

- The NIF reload mechanism is deprecated. Do not use it as an upgrade method for live production systems. It might be removed in future releases. It can still serve as a development feature but a warning message will be logged each time it is used.

  *** POTENTIAL INCOMPATIBILITY ***

  Own Id: OTP-9771

- The driver interface has been changed to enable 64-bit aware drivers. Most importantly the return types for ErlDrvEntry callbacks 'call' and 'control' has ben enlarged which require drivers to be changed or they will cause emulator crashes. See Rewrites for 64-bit driver interface in the driver manual.

  Due to this driver version management is now mandatory. A driver that is not written with version management or a driver that was compiled with the wrong major version will be not be loaded by the emulator.

  *** POTENTIAL INCOMPATIBILITY ***

  Own Id: OTP-9795

- Eliminate use of deprecated regexp module

  Own Id: OTP-9810

### 1.4 Erts 5.8.5

#### Fixed Bugs and Malfunctions

- Several bugs concerning constant binary constructions such as <<0:4294967295>> have been corrected. Depending on the actual size of the binary and the type of run-time system (32-bit, halfword, 64-bit), such expression could either crash the run-time system or make the loader refuse loading of the module.

  Own Id: OTP-9284

- The Erlsrv utility failed to stop the erlang machine if no StopAction was defined when the service was stopped. This is now corrected.

  Own Id: OTP-9344

- Due to a bug in glibc the runtime system could abort while trying to destroy a mutex. A fix for this was introduced in R14B02. This fix did, however, not solve the problem. The runtime system will now issue a warning instead of aborting.

  Own Id: OTP-9373 Aux Id: OTP-9009

- Replace atom in DRV macro in prim_file with string

  An experimental version of Dialyzer discovered that the atom that replaced the DRV macro in prim_file ends up in calls to erlang:open_port({spawn, Driver}, Portopts) as the Driver argument. The documentation states that this call requires a string there.

  This change is also consistent with the one introduced in commit 0f03b1e9d2bef3bc830c31a369261af4c5234727 by Kostis Sagonas.

  Own Id: OTP-9377

- Fix typos in the epmd documentation (Thanks to Holger Weiß )

  Own Id: OTP-9387

- Fix faulty integer terms created by NIF API from 64-bit integers on halfword emulator. (Thanks to Paolo Negri and Paul Davis)

  Own Id: OTP-9394

- Fix epmd crash on vxworks caused by faulty argument to select() system call.

  Own Id: OTP-9427 Aux Id: seq11855

- The ets:test_ms function could in rare cases truncate the error messages. This is now corrected.

  Own Id: OTP-9435

- Fix bug related to hibernate and HiPE (clear F_HIBERNATE_SCHED flag)

  F_HIBERNATE_SCHED flag that was introduced in b7ecdcd1ae9e11b8f75e must be cleared in hipe_mode_switch as well. Otherwise, processes running HiPE code that hibernate, wake up and then trap into a BIF will not be rescheduled.(Thanks to Paul Guyot)

  Own Id: OTP-9452

- Fix bug in FreeBSD topology detection code (Thanks to Paul Guyot)

  Own Id: OTP-9453

- Fix use of logical operator && with constant operand instead of bitwise & (Thanks to Cristian Greco)

  Own Id: OTP-9454

- inet: error if fd does not match socket domain

  If an IPv4 fd is opened as an IPv6 socket, unexpected behaviour can occur. For example, if an IPv4 UDP socket is opened and passed into Erlang as an IPv6 socket, the first 3 bytes (corresponding to 1 byte representing the protocol family, 2 bytes set to the port) are stripped from the payload. The cause of the UDP payload truncation happens in inet_drv.c:packet_inet_input when a call to inet_get_address fails silently because the family is set to PF_INET6 but the buffer len is the size of an IPv4 struct sockaddr_in.

  (Thanks to Andrew Tunnell-Jones for finding the bug and the test case!)

  Own Id: OTP-9455

- erts: use a union to avoid strict aliasing issues

  Use a union for pointer type conversion to avoid compiler warnings about strict-aliasing violations with gcc-4.1. gcc >= 4.2 does not emit the warning. erts: adapt matrix_nif to R14 erl_nif API changes (Thanks To Tuncer Ayaz)

  Own Id: OTP-9487

- fix 64-bit issues in the garbage collection (Thanks to Richard Carlsson)

  Own Id: OTP-9488

- epmd: fix compiler warnings

  Suppress compiler warnings about ignored return values. (Thanks to Michael Santos )

  Own Id: OTP-9500

- Fix non-existing function (erlang:disconnect/1) in distributed reference manual (Thanks to Fabian Król)

  Own Id: OTP-9504

- Document fdatasync -lrt requirement (SunOS <= 5.10) (Thanks to Tuncer Ayaz)

  Own Id: OTP-9512

- Let epmd ignore empty ERL_EPMD_ADDRESS

  If the environment variable ERL_EPMD_ADDRESS is set to the empty string, empd now behaves like it does by default when ERL_EPMD_ADDRESS is unset. That is, in this case, epmd now listens on all available interfaces instead of using only the loopback interface, which happened because epmd added the loopback address to the (in this case empty) list of addresses specified via ERL_EPMD_ADDRESS.

  Also, epmd now ignores ERL_EPMD_ADDRESS if it contains only separator characters (comma and space).

  The same applies to epmd's -address option.(Thanks to Holger Weiß)

  Own Id: OTP-9525

- Remove dead code in erl_compile (Thanks to Tuncer Ayaz)

  Own Id: OTP-9527

- Add erlang:external_size/2 BIF

  This BIF's second parameter is a list of options. Currently the only allowed option is {minor_version, Version} where version is either 0 (default) or 1. (Thanks to Filipe David Manana )

  Own Id: OTP-9528

- Fix enif_compare on 64bits machines

  In 64bits machines the Sint type has a size of 8 bytes, while on 32bits machines it has a 4 bytes size. enif_compare was ignoring this and therefore returning incorrect values when the result of the CMP function (which returns a Sint value) doesn't fit in 4 bytes. (Thanks to Filipe David Manana)

  Own Id: OTP-9533

- Implement or fix -Werror option

  If -Werror is enabled and there are warnings no output file is written. Also make sure that error/warning reporting is consistent. (Thanks to Tuncer Ayaz)

  Own Id: OTP-9536

- In some rare cases we did not have a run queue when scheduling misc ops. This is now fixed.

  Own Id: OTP-9537

- Remove misc. compiler warnings

  Own Id: OTP-9542

- Two bugs in gen_sctp has been corrected: getopts/setopts hence also send could only be called from socket owner, and options 'linger', 'rcvbuf' and 'sndbuf' was read from wrong protocol layer hence read wrong values by getopts.

  Own Id: OTP-9544

- Erlang/OTP can now be built on MacOS X Lion.

  Own Id: OTP-9547

- XML files have been corrected.

  Own Id: OTP-9550 Aux Id: OTP-9541

- Fix potential errors inspired by running cppcheck(1) (Thanks to Christian von Roques)

  Own Id: OTP-9557

- When auxiliary work was enqueued on a scheduler, the wakeup of the scheduler in order to handle this work could be lost. Wakeups in order to handle ordinary work were not effected by this bug. The bug only effected runtime systems with SMP support as follows:

  - Deallocation of some ETS data structures could be delayed.
  - On Linux systems not using the NPTL thread library (typically ancient systems with kernel versions prior to 2.6) and Windows systems, the {Port, {exit_status, Status}} message from a terminating port program could be delayed. That is, it only effected port programs which had been started by passing exit_status as an option to open_port/2.

  Own Id: OTP-9567

- Handle rare race in the crypto key server functionality

  Own Id: OTP-9586

#### Improvements and New Features

- Types and specifications have been added.

  Own Id: OTP-9356

- New allocator strategy "address order first fit". May ease the emptying of memory carriers and thereby real release of memory back to the OS.

  Own Id: OTP-9424

- The new erlang:check_old_code/1 BIF checks whether a module has old code.

  Own Id: OTP-9495

- Update documentation and specifications of some of the zlib functions.

  Own Id: OTP-9506

- Detect the available CPUs on IRIX

  Add support for querying the number of configured and online processors on SGI systems running IRIX.(Thanks to Holger Weiß)

  Own Id: OTP-9531

### 1.5 Erts 5.8.4

#### Fixed Bugs and Malfunctions

- Fix binary and iolist overflow problems. Typically problems arose in length calculation where the result would exceed (1 bsl 32 - 1).

  Own Id: OTP-9118

- Using the old erlang shell (i.e. erl instead on werl) on windows and doing several init:restart's would eventually hang the VM. That is no longer the case.

  Own Id: OTP-9139

- Removed recursive C code when printing Erlang terms to buffers, avoiding stack overflows that could cause VM to crash.

  Own Id: OTP-9140

- The send_timeout option in gen_tcp did not work properly in active mode or with {active,once} options. This is now corrected.

  Own Id: OTP-9145

- Fixed various typos across the documentation (Thanks to Tuncer Ayaz)

  Own Id: OTP-9154

- Remove duplicate stack entries which could occur after calling certain BIFs.

  Own Id: OTP-9163

- A race when starting two nodes simultaneously using run_erl has been removed.

  Own Id: OTP-9164

- Add documentation on .erlang processing back again (Thanks to Gabor Liptak)

  Own Id: OTP-9189

- Remove gratuitous paren in driver_entry(Thanks to Tuncer Ayaz)

  Own Id: OTP-9192

- Fix some wrong pointer dereferences (Thanks to Cristian Greco)

  Own Id: OTP-9194

- erts: Remove unused variables (Thanks to Tuncer Ayaz)

  Own Id: OTP-9205

- The documentation for init:get_args/0 has been removed. init:get_args/0 itself was deprecated in R9C and removed in R12B. (Thanks to Eric Pailleau.)

  Own Id: OTP-9209

- Allow user to specify the IP address epmd binds to

  The IP address(es) epmd binds to can now be specified by the user, either via epmd's new "-address" option or (if that's not used) by setting the environment variable ERL_EPMD_ADDRESS. Multiple addresses may be specified using a comma-separated list. If the loopback address is not in this list, it will be added implicitly, so that the daemon can be queried by an interactive epmd process.(Thanks to Holger Weiß)

  Own Id: OTP-9213

- epmd: include host address in local access check

  In FreeBSD jails, the source and destination address of connections to localhost are changed to be the IP address of the jail. Consider connections from the host's IP address to itself (e.g., the source and destination address match) to be local for the access control checks. (Thanks to Michal Santos and Tom at diogunix.com)

  Own Id: OTP-9214

- Fix list returned by net_kernel:epmd_module

  Function epmd_module of net_kernel returns a list instead of an atom, when the epmd_module-flag is used. (Thanks to Markus Knofe)

  Own Id: OTP-9215

- Fix epmd's dbg_perror() output

  The dbg_perror() function now hands the current errno value over to dbg_gen_printf(). This fixes the problem that errno had been reset to zero by the time it was used (to print the corresponding error message) in the dbg_gen_printf() function. (Thanks to Holger Weiß)

  Own Id: OTP-9223

- heart: remove garbage appended to heart command

  heart:get_cmd/0 is documented to return an empty string if the command is cleared. get_cmd/0 returns 2 extra bytes: 1 byte for the trailing null, 1 byte from the op (the op is an unsigned char and 2 bytes are allocated for it in the returned buffer). (Thanks to Michael Santos)

  Own Id: OTP-9224

- file: fix hang reading compressed files

  The gzio driver goes into an infinite loop when reading past the end of a compressed file. Reported-By: Alex Morarash (Thanks to Michael Santos)

  Own Id: OTP-9245

- Eliminate alias warnings from gcc 4.5.2

  Own Id: OTP-9250

- Unsigned integer may overflow in error message (Thanks to Michael Santos)

  Own Id: OTP-9251

- Driver names should be strings, not atoms

  Own Id: OTP-9253

- driver_entry: Remove gratuitous paren and fix typo (Thanks to Tuncer Ayaz)

  Own Id: OTP-9254

- Fix format specifiers in erl_exit messages

  Fix an error message by using an unsigned integer specifier as seen in a tweet by @metabrew: #erlang VM crashed with "no next heap size found: -2090496108, offset 0", suddenly allocated all available RAM

  Also correct mis-typed string formats in bif.c.(Thanks to Michael Santos)

  Own Id: OTP-9262

- net_drv: remove unused tcp request id inet_drv: remove gratuitous assignment (Thanks to Tuncer Ayaz)

  Own Id: OTP-9263

- Teach run_erl RUN_ERL_DISABLE_FLOWCNTRL for disabling flow control

  Flow control can cause unwanted behaviour of the beam process, if accidentally hit Ctrl-S (instead of Ctrl-D to detach) the entire beam may be blocked.

  Fix this problem by making it possible to turn off flow control by setting the environment variable RUN_ERL_DISABLE_FLOWCNTRL. (Thanks to Jonas Faklkevik)

  Own Id: OTP-9270

- The following bugs due to missing memory barriers have been fixed:

  - ETS tables using the write_concurrency option could potentially get into an internally inconsistent state.

  - ETS tables using the ordered_set option could potentially get into an internally inconsistent state.

  - A number of memory barriers have been added when building with the libatomic_ops API (i.e. when passing --with-libatomic_ops=PATH to configure) and the tilera atomics API (i.e. when building for the tilera chip). Note that these bugs were due to erroneous usage of the APIs, and not in the implementations of the APIs. When using these APIs the following bugs where present:

    - The BIF erlang:ports/0 could return an erroneous result.

    - A thread blocking other threads during code loading, or setup of tracing could potentially read invalid data.

    - Fixation of ETS tables could potentially get into an internally inconsistent state.

  Own Id: OTP-9281

- Fix halfword bug for ETS ordered_set when doing select/match with partly bound key.

  Own Id: OTP-9292

- Fix bug in code:is_module_native that caused crash for deleted modules.

  Own Id: OTP-9298

- Calling driver_async_cancel() could cause a scheduler thread to enter an eternal loop doing no useful work. (Thanks to Anders Ramsell)

  Own Id: OTP-9302

#### Improvements and New Features

- New enif_is_exception function to allow NIFs to determine whether an ERL_NIF_TERM represents an exception. (Thanks to Steve Vinoski)

  Own Id: OTP-9150

- A process being garbage collected by another process could be scheduled on another scheduler. This prevented this scheduler from doing any useful work until the garbage collection was done. This either occurred due to a explicit call to the garbage_collect/1 BIF, or due to a garbage collection part of code loading. A process being garbage collected like this will now not be scheduled until the garbage collection has completed.

  Own Id: OTP-9211

- Remove unnecessary validation copy in prim_file:drv_command/3 (Thanks to Tony Rogvall)

  Own Id: OTP-9276

- Symbolic link handling on windows have been slightly updated to map error conditions more consequently and correctly read directory links created outside of the Erlang environment.

  Own Id: OTP-9279

- Due to standard library DLL mismatches between versions of OpenSSL and Erlang/OTP, OpenSSL is now linked statically to the crypto driver on Windows. This fixes problems starting crypto when running Erlang as a service on all Windows versions.

  Own Id: OTP-9280

- Halfword emulator memory handling improvements:

  - Much more of internal memory structures have been made able to use "high" memory and are no longer restricted to the 4Gb limit that still applies for all process heap data.

  - Fixed faulty values from erlang:memory() caused by 32-bit counter overflow.

  - New counter low in erlang:memory() that sums up all memory restricted by 4Gb limit.

  Own Id: OTP-9291 Aux Id: seq11841

- The value set in the undocumented and unsupported ERL_version_FLAGS (e.g. ERL_R14B03_FLAGS) environment variable can now be overridden by the command line (similar to ERL_AFLAGS).

  Own Id: OTP-9297

### 1.6 Erts 5.8.3.2

#### Known Bugs and Problems

- Fix halfword emulator bug in ets:select_delete for ordered_set that caused emulator to crash.

  Own Id: OTP-9258 Aux Id: seq11836

### 1.7 Erts 5.8.3.1

#### Fixed Bugs and Malfunctions

- Ets table type ordered_set could order large integer keys wrongly on pure 64bit platforms. This is now corrected.

  Own Id: OTP-9181

- The status of a process was unnecessarily set to waiting before a process was enqueued in a run queue. This bug was harmless up until OTP-R14B01. In OTP-R14B02 erlang:hibernate/3 was fixed (OTP-9125). After the introduction of OTP-9125, the previously harmless process status bug sometimes caused erroneous badarg exceptions from process_info().

  OTP-9125 also introduced a thread unsafe access to the status field of a process which now also have been fixed.

  *** INCOMPATIBILITY with noxs ***

  Own Id: OTP-9197

### 1.8 Erts 5.8.3

#### Fixed Bugs and Malfunctions

- The scroll wheel now scrolls the werl window on Windows.

  Own Id: OTP-8985

- Some malformed distribution messages could cause VM to crash, this is now corrected.

  Own Id: OTP-8993

- The OS function getifaddrs() can return NULL in some address fields for e.g PPP and tunnel devices which caused the emulator to segfault. This bug has now been corrected.

  Own Id: OTP-8996

- The expression <<A:0>> would always produce an empty binary, even if A was not an integer. Corrected to cause a badarg exception if the type of A is invalid. (Thanks to Zvi.)

  Own Id: OTP-8997

- A bug that potentially could cause an emulator crash when deleting an ETS-table has been fixed. A resource leak when hitting the maximum amount of ETS-tables allowed has also been fixed.

  Own Id: OTP-8999

- A bug in the exit/2 BIF could potentially cause an emulator crash.

  Own Id: OTP-9005

- Due to a bug in glibc the runtime system could abort while trying to destroy a mutex. The runtime system will now issue a warning instead of aborting.

  Own Id: OTP-9009

- A bug in epmd could create strange behaviour when listen() calls failed. This is now corrected thanks to Steve Vinoski.

  Own Id: OTP-9024

- When setting file_info the win32_driver will now correctly set access and modified time. Previously these entities were swapped.

  Own Id: OTP-9046

- Setting scheduler bind type to unbound failed if binding of schedulers wasn't supported, or if CPU topology wasn't present. This even though the documentation stated that it is possible to set the bind type to unbound.

  Own Id: OTP-9056 Aux Id: Seq11779

- Two problems were fixed in crash dump: The time left for timers are now shown as unsigned integers and the contents of ordered_set ETS tables is no longer included.

  Own Id: OTP-9057

- The VM could fail to set IP_TOS and SO_PRIORITY in certain situations, either because sockets were supplied as open file descriptors, or because SO_PRIORITY by default was set higher than the user can explicitly set it to. Those situations are now handled.

  Own Id: OTP-9069

- Wx on MacOS X generated complains on stderr about certain cocoa functions not beeing called from the "Main thread". This is now corrected.

  Own Id: OTP-9081

- Fix a couple typos in driver_entry(3) (thanks to Tuncer Ayaz).

  Own Id: OTP-9085

- Mention that "-detached" implies "-noinput"

  Clarify that specifying "-noinput" is unnecessary if the "-detached" flag is given. (thanks to Holger Weiß)

  Own Id: OTP-9086

- A potential problem (found by code inspection) when calling a fun whose code was not loaded has been fixed.

  Own Id: OTP-9095

- The emulator could get into a state where it didn't check for I/O.

  Own Id: OTP-9105 Aux Id: Seq11798

- Attempting to create binaries exceeding 2Gb (using for example term_to_binary/1) would crash the emulator with an attempt to allocate huge amounts of memory. (Thanks to Jon Meredith.)

  Own Id: OTP-9117

- Fix erlang:hibernate/3 on HiPE enabled emulator (Thanks to Paul Guyot)

  Own Id: OTP-9125

#### Improvements and New Features

- From this release, the previously experimental halfword emulator is now official. It can be enabled by giving the --enable-halfword-emulator option to the configure script.

  The halfword emulator is a 64-bit application, but uses halfwords (32-bit words) for all data in Erlang processes, therefore using less memory and being faster than the standard 64-bit emulator. The total size of all BEAM code and all process data for all processes is limited to 4Gb, but ETS tables and off-heap binaries are only limited by the amount of available memory.

  Own Id: OTP-8941

- 32-bit atomic memory operations have been introduced internally in the run time system, and are now used where appropriate. There were previously only atomic memory operations of word size available. The 32-bit atomic memory operations slightly reduce memory consumption, and slightly improve performance on 64-bit runtime systems.

  Own Id: OTP-8974

- Performance enhancements for looking up timer-entries and removing timers from the wheel.

  Own Id: OTP-8990

- Write accesses to ETS tables have been optimized by reducing the amount of atomic memory operations needed during a write access.

  Own Id: OTP-9000

- Strange C coding in the VM made the -D_FORTIFY_SOURCE option to gcc-4.5 react badly. The code is now cleaned up so that it's accepted by gcc-4.5.

  Own Id: OTP-9025

- The memory footprint for loaded code has been somewhat reduced (especially in the 64-bit BEAM machine).

  Own Id: OTP-9030

- The maximum number of allowed arguments for an Erlang function has been lowered from 256 to 255, so that the number of arguments can now fit in a byte.

  Own Id: OTP-9049

- Dependency generation for Makefiles has been added to the compiler and erlc. See the manual pages for compile and erlc. (Thanks to Jean-Sebastien Pedron.)

  Own Id: OTP-9065

### 1.9 Erts 5.8.2

#### Fixed Bugs and Malfunctions

- Fix format_man_pages so it handles all man sections and remove warnings/errors in various man pages.

  Own Id: OTP-8600

- The configure command line argument --enable-ethread-pre-pentium4-compatibility had no effect. This option is now also automatically enabled if required on the build machine.

  Own Id: OTP-8847

- Windows 2003 and Windows XP pre SP3 would sometimes not start the Erlang R14B VM at all due to a bug in the cpu topology detection. The bug affects Windows only, no other platform is even remotely affected. The bug is now corrected.

  Own Id: OTP-8876

- The HiPE run-time in the 64-bit emulator could do a 64-bit write to a 32-bit struct field. It happened to be harmless on Intel/AMD processors. Corrected. (Thanks to Mikael Pettersson.)

  Own Id: OTP-8877

- A bug in erl_drv_tsd_get() and enif_tsd_get() could cause an emulator crash. These functions are currently not used in OTP. That is, the crash only occur on systems with user implemented NIF libraries, or drivers that use one of these functions.

  Own Id: OTP-8889

- Calling erlang:system_info({cpu_topology, CpuTopologyType}) with another CpuTopologyType element than one of the documented atoms defined, detected, or used caused an emulator crash. (Thanks to Paul Guyot)

  Own Id: OTP-8914

- The ERTS internal rwlock implementation could get into an inconsistent state. This bug was very seldom triggered, but could be during heavy contention. The bug was introduced in R14B (erts-5.8.1).

  The bug was most likely to be triggered when using the read_concurrency option on an ETS table that was frequently accessed from multiple processes doing lots of writes and reads. That is, in a situation where you typically don't want to use the read_concurrency option in the first place.

  Own Id: OTP-8925 Aux Id: OTP-8544

- Tracing to port could cause an emulator crash when unloading the trace driver.

  Own Id: OTP-8932

- Removed use of CancelIoEx on Windows that had been shown to cause problems with some drivers.

  Own Id: OTP-8937

- The fallback implementation used when no native atomic implementation was found did not compile. (Thanks to Patrick Baggett, and Tuncer Ayaz)

  Own Id: OTP-8944

- Some integer values used during load balancing could under rare circumstances wrap causing a load unbalance between schedulers.

  Own Id: OTP-8950

- The windows VM now correctly handles appending to large files (> 4GB).

  Own Id: OTP-8958

- Name resolving of IPv6 addresses has been implemented for Windows versions that support it. The use of ancient resolver flags (AI_V4MAPPED | AI_ADDRCONFIG) to the getaddrinfo() function has been removed since e.g FreeBSD regard mapped IPv4 addresses to be a security problem and the semantics of the address configured flag is uncertain.

  Own Id: OTP-8969

#### Improvements and New Features

- The help texts produced by the configure scripts in the top directory and in the erts directory have been aligned and cleaned up.

  Own Id: OTP-8859

- When the runtime system had fewer schedulers than logical processors, the system could get an unnecessarily large amount reader groups.

  Own Id: OTP-8861

- run_rel has been updated to support Solaris's /dev/ptmx device and to load the necessary STREAMS modules so that to_erl can provide terminal echo of keyboard input. (Thanks to Ryan Tilder.)

  Own Id: OTP-8878

- The Erlang VM now supports Unicode filenames. The feature is turned on by default on systems where Unicode filenames are mandatory (Windows and MacOSX), but can be enabled on other systems with the '+fnu' emulator option. Enabling the Unicode filename feature on systems where it is not default is however considered experimental and not to be used for production. Together with the Unicode file name support, the concept of "raw filenames" is introduced, which means filenames provided without implicit unicode encoding translation. Raw filenames are provided as binaries, not lists. For further information, see stdlib users guide and the chapter about using Unicode in Erlang. Also see the file module manual page.

  *** POTENTIAL INCOMPATIBILITY ***

  Own Id: OTP-8887

- Buffer overflows have been prevented in erlc, dialyzer, typer, run_test, heart, escript, and erlexec.

  (Thanks to Michael Santos.)

  Own Id: OTP-8892

- The runtime system is now less eager to suspend processes sending messages over the distribution. The default value of the distribution buffer busy limit has also been increased from 128 KB to 1 MB. This in order to improve throughput.

  Own Id: OTP-8901

- The distribution buffer busy limit can now be configured at system startup. For more information see the documentation of the erl +zdbbl command line flag. (Thanks to Scott Lystig Fritchie)

  Own Id: OTP-8912

- The inet driver internal buffer stack implementation has been rewritten in order to reduce lock contention.

  Own Id: OTP-8916

- New ETS option compressed, to enable a more compact storage format at the expence of heavier table operations. For test and evaluation, erl +ec can be used to force compression on all ETS tables.

  Own Id: OTP-8922 Aux Id: seq11658

- There is now a new function inet:getifaddrs/0 modeled after C library function getifaddrs() on BSD and LInux that reports existing interfaces and their addresses on the host. This replaces the undocumented and unsupported inet:getiflist/0 and inet:ifget/2.

  Own Id: OTP-8926

- Support for detection of CPU topology and binding of schedulers on FreeBSD 8 have been added. (Thanks to Paul Guyot)

  Own Id: OTP-8939

- Several bugs related to hibernate/3 and HiPE have been corrected. (Thanks to Paul Guyot.)

  Own Id: OTP-8952

- Support for soft and hard links on Windows versions and filesystems that support them is added.

  Own Id: OTP-8955

- The win32 virtual machine is now linked large address aware. his allows the Erlang VM to use up to 3 gigs of address space on Windows instead of the default of 2 gigs.

  Own Id: OTP-8956

### 1.10 Erts 5.8.1.2

#### Fixed Bugs and Malfunctions

- Fix that the documentation top index generator can handle an Ericsson internal application group.

  Own Id: OTP-8875

- In embedded mode, on_load handlers that called code:priv_dir/1 or other functions in code would hang the system. Since the crypto application now contains an on_loader handler that calls code:priv_dir/1, including the crypto application in the boot file would prevent the system from starting.

  Also extended the -init_debug option to print information about on_load handlers being run to facilitate debugging.

  Own Id: OTP-8902 Aux Id: seq11703

### 1.11 Erts 5.8.1.1

#### Fixed Bugs and Malfunctions

- Windows 2003 and Windows XP pre SP3 would sometimes not start the Erlang R14B VM at all due to a bug in the cpu topology detection. The bug affects Windows only, no other platform is even remotely affected. The bug is now corrected.

  Own Id: OTP-8876

### 1.12 Erts 5.8.1

#### Fixed Bugs and Malfunctions

- Very small floating point numbers generated errors when converting from list to float in some versions of the VM, this is now corrected so that i.e. list_to_float("1.0e-324"). returns 0.0 in all versions of Erlang.

  Own Id: OTP-7178

- Windows Vista and Windows 7 file system virtualization, which makes "old style" windows programs execute in a file system sandbox, was previously unintentionally turned on for the Erlang VM. This is now corrected so that i.e. writes to C:\Program Files\. without administrator privileges will fail.

  Own Id: OTP-7405

- Fix faulty 64-bit integer term output from drivers. Large 64-bits integers did not generate correct bignums and could even cause emulator crash. Only affects drivers using ERL_DRV_INT64 or ERL_DRV_UINT64, introduced in R13B03.

  Own Id: OTP-8716

- Fixed: inet:setopts(S, [{linger,{true,2}}]) returned {error,einval} for SCTP sockets. The inet_drv had a bug when checking the option size.

  Own Id: OTP-8726 Aux Id: seq11617

- Fix libm linking with --as-needed flag

  When building with "--as-needed" linker flags on Linux the build will fail. This has now been fixed.

  (Thanks to Christian Faulhammer)

  Own Id: OTP-8728

- gen_udp:connect/3 was broken for SCTP enabled builds. It did not detect remote end errors as it should.

  Own Id: OTP-8729

- Reduce the risk of integer wrapping in bin vheap size counting.

  The vheap size series will now use the golden ratio instead of doubling and fibonacci sequences.

  Own Id: OTP-8730

- ETS ordered_set containing [] as key could cause strange thing to happen, like an infinite hanging ets:select.

  Own Id: OTP-8732

- reference() has been substituted for ref() in the documentation.

  Own Id: OTP-8733

- When a native compiled module called a not loaded non-native compiled module that had an on_load function, the export entries were trashed after code loading so on the next call from the native compiled module to the non-native compiled the emulator crashed. This bug has now been fixed.

  Own Id: OTP-8736

- HiPE-enabled Erlang VMs running on BSD systems sometimes generated messages like "Yikes! erts_alloc() returned misaligned address 0x8016a512c". Fixed. (Thanks to Mikael Pettersson.)

  Own Id: OTP-8769

- A race condition in erts_poll() could cause delay of poll for I/O.

  Own Id: OTP-8773

- Removed some potential vulnerabilities from the Erlang Port Mapper Daemon (epmd) and straightened up access control. Also removed hazardous interfaces allowing anyone on a machine to forcefully unregister other nodes. This means that the ei_unregister/erl_unregister interfaces in erl_interface is rendered not only error prone and mystifying as before, but totally ineffective. The old behaviour of unchecked node unregistering can be restored if needed, see epmd documentation for details.

  *** POTENTIAL INCOMPATIBILITY ***

  Own Id: OTP-8780

- Building in a source tree without prebuilt platform independent build results failed on the SSL examples when:

  - cross building. This has been solved by not building the SSL examples during a cross build.
  - building on Windows.

  Own Id: OTP-8791

- inet:getsockopt for SCTP sctp_default_send_param had a bug to not initialize required feilds causing random answers. It is now corrected.

  Own Id: OTP-8795 Aux Id: seq11655

- The hipe_bifs:get_hrvtime/0 BIF now always returns a real value even if the "perfctr" Linux kernel extension is not available. It used to return a dummy value. (Thanks to Mikael Pettersson.)

  Own Id: OTP-8798

- Calling a native-code compiled module with an on_load function could cause a crash. (Thanks to Mikael Pettersson.)

  Own Id: OTP-8799

- The emulator could crash while writing a crash dump if native-compiled modules had been loaded. (Thanks to Paul Guyot.)

  Own Id: OTP-8801

- The garbage collector could crash if invoked from native-compiled code after a call to a BIF. (Thanks to Paul Guyot.)

  Own Id: OTP-8821

- A rare memory leak in binary:matches is removed

  Own Id: OTP-8823

- For a socket in the HTTP packet mode, the return value from gen_tcp:recv/2,3 if there is an error in the header will be {ok,{http_error,String}} instead of {error,{http_error,String}} to be consistent with ssl:recv/2,3.

  *** POTENTIAL INCOMPATIBILITY ***

  Own Id: OTP-8831

#### Improvements and New Features

- ets:select_reverse/{1,2,3} are now documented.

  Own Id: OTP-7863

- External format of integers changed to make full use of all 32 bits of INTEGER_EXT. This is a compatible change as old code can read full 32-bit integers but only produce 28-bit integers as INTEGER_EXT.

  Own Id: OTP-8540 Aux Id: seq11534

- Large parts of the ethread library have been rewritten. The ethread library is an Erlang runtime system internal, portable thread library used by the runtime system itself.

  Most notable improvement is a reader optimized rwlock implementation which dramatically improve the performance of read-lock/read-unlock operations on multi processor systems by avoiding ping-ponging of the rwlock cache lines. The reader optimized rwlock implementation is used by miscellaneous rwlocks in the runtime system that are known to be read-locked frequently, and can be enabled on ETS tables by passing the {read_concurrency, true} option upon table creation. See the documentation of ets:new/2 for more information. The reader optimized rwlock implementation can be fine tuned when starting the runtime system. For more information, see the documentation of the +rg command line argument of erl.

  There is also a new implementation of rwlocks that is not optimized for readers. Both implementations interleaves readers and writers during contention as opposed to, e.g., the NPTL (Linux) pthread rwlock implementation which use either a reader or writer preferred strategy. The reader/writer preferred strategy is problematic since it starves threads doing the non-preferred operation.

  The new rwlock implementations in general performs better in ERTS than common pthread implementations. However, in some extremely heavily contended cases this is not the case. Such heavy contention can more or less only appear on ETS tables. This when multiple processes do very large amounts of write locked operations simultaneously on the same table. Such use of ETS is bad regardless of rwlock implementation, will never scale, and is something we strongly advise against.

  The new rwlock implementations depend on atomic operations. If no native atomic implementation is found, a fallback solution will be used. Using the fallback implies a performance degradation. That is, it is more important now than before to build OTP with a native atomic implementation.

  The ethread library contains native atomic implementations for, x86 (32 and 64 bit), powerpc (32 bit), sparc V9 (32 and 64 bit), and tilera (32 bit). On other hardware gcc's builtin support for atomic memory access will be used if such exists. If no such support is found, configure will warn about no atomic implementation available.

  The ethread library can now also use the libatomic_ops library for atomic memory accesses. This makes it possible for the Erlang runtime system to utilize optimized native atomic operations on more platforms than before. If configure warns about no atomic implementation available, try using the libatomic_ops library. Use the --with-libatomic_ops=PATH configure command line argument when specifying where the libatomic_ops installation is located. The libatomic_ops library can be downloaded from: http://www.hpl.hp.com/research/linux/atomic_ops/

  The changed API of the ethread library has also caused modifications in the Erlang runtime system. Preparations for the to come "delayed deallocation" feature has also been done since it depends on the ethread library.

  Note: When building for x86, the ethread library will now use instructions that first appeared on the pentium 4 processor. If you want the runtime system to be compatible with older processors (back to 486) you need to pass the --enable-ethread-pre-pentium4-compatibility configure command line argument when configuring the system.

  Own Id: OTP-8544

- erlang:localtime_to_universaltime({{2008, 8, 1}, {0, 0, 0}},true) when TZ=UTC now behaves consistently on all Unix platforms.

  The problem fixed was originally reported by Paul Guyot on erlang-bugs mailing list:

  http://www.erlang.org/pipermail/erlang-bugs/2008-November/001077.html

  Own Id: OTP-8580

- Optimization reducing memory consumption by two words per ETS object.

  Own Id: OTP-8737

- Fixes for unsupported halfword-emulator

  Own Id: OTP-8745

- NIF 64-bit integer support; enif_get_int64, enif_get_uint64, enif_make_int64, enif_make_uint64.

  Own Id: OTP-8746

- Alignment of trailing data in messages has been adjusted. This in order to be able to pass data of any type as trailing data in the future.

  Own Id: OTP-8754

- The obsolete/driver.h header file has been removed. It has been obsolete and deprecated since R8B. Drivers that still include obsolete/driver.h must be updated to include erl_driver.h.

  *** POTENTIAL INCOMPATIBILITY ***

  Own Id: OTP-8758

- Added erlang:system_info(build_type) which makes it easier to chose drivers, NIF libraries, etc based on build type of the runtime system.

  The NIF library for crypto can now be built for valgrind and/or debug as separate NIF libraries that will be automatically loaded if the runtime system has been built with a matching build type.

  Own Id: OTP-8760

- Further lessened the memory requirements of ETS objects.

  Own Id: OTP-8762

- The broken elib_malloc alternate memory allocator has been removed. erlang:system_info(elib_malloc) will always return false, and in R15, erlang:system_info(elib_malloc) will fail with a badarg exception.

  Own Id: OTP-8764

- Calling erlang:system_info/1 with the new argument update_cpu_info will make the runtime system reread and update the internally stored CPU information. For more information see the documentation of erlang:system_info(update_cpu_info).

  The CPU topology is now automatically detected on Windows systems with less than 33 logical processors. The runtime system will now, also on Windows, by default bind schedulers to logical processors using the default_bind bind type if the amount of schedulers is at least equal to the amount of logical processors configured, binding of schedulers is supported, and a CPU topology is available at startup.

  Own Id: OTP-8765

- The SMP ERTS internal child waiter thread used on Linux system with NPTL was unintentionally disabled during cross compilation rewrites (OTP-8323 in R13B03). It has now been re-enabled. Enabling it again gives a slight performance improvement.

  Own Id: OTP-8774

- epmd used to generate a message to the syslog when it started up, which could be annoying. This has been changed to only generate the message if the debug swith is given. (Thanks to Michael Santos.)

  Own Id: OTP-8775

- The scheduler wakeup threshold is now possible to adjust at system boot. For more information see the +swt command line argument of erl.

  Own Id: OTP-8811

- The undocumented function inet:ifget/2 has been improved to return interface hardware address (MAC) on platforms supporting getaddrinfo() (such as BSD unixes). Note it still does not work on all platforms for example not Windows nor Solaris, so the function is still undocumented.

  Buffer overflow and field init bugs for inet:ifget/2 and inet:getservbyname/2 has also been fixed.

  Thanks to Michael Santos.

  Own Id: OTP-8816

- Optimizations for MIPS when using gcc atomics. (Thanks to Steve Vinoski)

  Own Id: OTP-8834

- Lock optimization in timer functionality.

  Own Id: OTP-8835

#### Known Bugs and Problems

- Fix epmd and build environment to build on VxWorks

  Own Id: OTP-8838

### 1.13 Erts 5.8

#### Fixed Bugs and Malfunctions

- Driver threads, such as async threads, using port data locks peeked at the port status field without proper locking when looking up the driver queue.

  Own Id: OTP-8475

- The use of mmap() was unnecessarily disabled when cross compiling.

  The configure arguments --with-ssl, and --with-odbc refused to accept libraries outside of $erl_xcomp_sysroot when cross compiling for no good reason.

  The configure argument --with-odbc didn't handle the value yes correct.

  The configure arguments --with-odbc, and --without-odbc have also been added to the configure help.

  (Thanks to Steve Vinoski for reporting these issues)

  Own Id: OTP-8484

- A call to the BIF unregister(RegName) when a port had the name RegName registered in the runtime system without SMP support caused a runtime system crash. (Thanks to Per Hedeland for the bugfix and test case.)

  Own Id: OTP-8487

- The runtime system crashed if fewer logical processors were found than reported by sysconf( SC_NPROCESSORS_CONF).

  Own Id: OTP-8549

- Fix memory management bug causing crash of non-SMP emulator with async threads enabled. The bug did first appear in R13B03.

  Own Id: OTP-8591 Aux Id: seq11554

- Port locks could be prematurely destroyed.

  Own Id: OTP-8612

- The empd program could loop and consume 100% CPU time if an unexpected error ocurred in listen() or accept(). Now epmd will terminate if a non-recoverable error occurs. (Thanks to Michael Santos.)

  Own Id: OTP-8618

- When kernel poll has been enabled, a livelock could in rare circumstances occur. Problem reported by Chetan Ahuja, fix by Mikael Pettersson.

  Own Id: OTP-8632

- Windows: Closing port of program that stalled without reading all data could deadlock scheduler thread.

  Own Id: OTP-8641

- On some combination of Montavista Linux on Cavium Octeon processors, some socket-related system calls returned other numbers than -1 for errors. This caused a core dump in inet_drv.c. Now the code works around this problem.

  Own Id: OTP-8654

- Missing memory barriers in erts_poll() could cause the runtime system to hang indefinitely.

  Own Id: OTP-8658

- ethr_rwmutex_tryrlock() acquired and refused to acquire a lock with inverted logic. The lock was however never acquired in a thread unsafe manner. (Thanks to JR Zhang for noting this issue)

  Own Id: OTP-8662

- Extreme combinations of register/unregister in a highly parallell SMP application could crash the VM. The error is corrected.

  Own Id: OTP-8663

- On Windows, files are now opened with FILE_SHARE_DELETE to get closer to Unix semantics.

  Own Id: OTP-8667

- erlang:system_info(multi_scheduling) sometimes erroneously returned enabled when it should have returned blocked.

  Own Id: OTP-8675

- Fix bug causing erlang:decode_packet and enif_make_string to generate faulty strings with negative character values for ascii values larger than 127. (Thanks to Paul Guyot)

  Own Id: OTP-8685

- open_port/2 with the spawn and spawn_executable options can include an {env,Env} option. In some cases unsetting variables would not work on Unix (typically if more variables were unset than were actually present in the environment).

  Own Id: OTP-8701

- A user defined CPU topology set via a call to erlang:system_flag(cpu_topology, CPUTopology) was not properly verified, and could in worst case cause an emulator crash. The emulator crash could only occur when a user defined CPU topology already existed and was redefined.

  Own Id: OTP-8710

#### Improvements and New Features

- The grammar for match specifications in ERTS users guide only described the tracing dialect of match specifications. An informal grammar for the ETS dialect is added.

  Own Id: OTP-8086 Aux Id: seq11333

- The module binary from EEP31 (and EEP9) is implemented.

  Own Id: OTP-8217

- New NIF API function enif_make_new_binary

  Own Id: OTP-8474

- The guard BIF is_boolean/1 (introduced in R10B) has now been included in the lists of BIFs allowed in guards in the Reference Manual.

  Own Id: OTP-8477

- Added function zip:foldl/3 to iterate over zip archives.

  Added functions to create and extract escripts. See escript:create/2 and escript:extract/2.

  The undocumented function escript:foldl/3 has been removed. The same functionality can be achieved with the more flexible functions escript:extract/2 and zip:foldl/3.

  Record fields has been annotated with type info. Source files as been adapted to fit within 80 chars and trailing whitespace has been removed.

  Own Id: OTP-8521

- A regular expression with many levels of parenthesis could cause a buffer overflow. That has been corrected. (Thanks to Michael Santos.)

  Own Id: OTP-8539

- erlang:decode_packet(httph_bin,..) could return corrupt header strings or even crash the VM. This has been fixed. It only happened on 32-bit VM if the header name was unknown and between 16 and 20 characters long. Sockets with simular packet option did not suffer from this bug.

  Own Id: OTP-8548

- New NIF features:

  - Send messages from a NIF, or from thread created by NIF, to any local process (enif_send)
  - Store terms between NIF calls (enif_alloc_env, enif_make_copy)
  - Create binary terms with user defined memory management (enif_make_resource_binary)

  And some incompatible changes made to the API. For more information see the warning text in erl_nif(3).

  *** POTENTIAL INCOMPATIBILITY ***

  Own Id: OTP-8555

- If the 'fop' program (needed for building PDF files) cannot not be found, it is now possible to build the HTML and man pages anyway (there will also be dummy PDF files with no real content created). (Thanks to Tuncer Ayaz.)

  Own Id: OTP-8559

- When defining macros the closing right parenthesis before the dot is now mandatory.

  *** POTENTIAL INCOMPATIBILITY ***

  Own Id: OTP-8562

- Local and imported functions now override the auto-imported BIFs when the names clash. The pre R14 behaviour was that auto-imported BIFs would override local functions. To avoid that old programs change behaviour, the following will generate an error:

  - Doing a call without explicit module name to a local function having a name clashing with the name of an auto-imported BIF that was present (and auto-imported) before OTP R14A

  - Explicitly importing a function having a name clashing with the name of an autoimported BIF that was present (and autoimported) before OTP R14A

  - Using any form of the old compiler directive nowarn_bif_clash

  If the BIF was added or auto-imported in OTP R14A or later, overriding it with an import or a local function will only result in a warning,

  To resolve clashes, you can either use the explicit module name erlang to call the BIF, or you can remove the auto-import of that specific BIF by using the new compiler directive -compile({no_auto_import,[F/A]})., which makes all calls to the local or imported function without explicit module name pass without warnings or errors.

  The change makes it possible to add auto-imported BIFs without breaking or silently changing old code in the future. However some current code ingeniously utilizing the old behaviour or the nowarn_bif_clash compiler directive, might need changing to be accepted by the compiler.

  *** POTENTIAL INCOMPATIBILITY ***

  Own Id: OTP-8579

- A bug in re that could cause certain regular expression matches never to terminate is corrected. (Thanks to Michael Santos and Gordon Guthrie.)

  Own Id: OTP-8589

- The erlang:open_port spawn and spawn_executable directives can include an {env,Env} directive to set up environment variables for the spawned process. A bug prevented applications from using {env,Env} to set an environment variable whose value ended with a '=' (equal sign) character; the trailing equal sign was mistaken as an indication that an environment variable was to be cleared from the environment of the spawned process. (Thanks to Steve Vinoski.)

  Own Id: OTP-8614

- receive statements that can only read out a newly created reference are now specially optimized so that it will execute in constant time regardless of the number of messages in the receive queue for the process. That optimization will benefit calls to gen_server:call(). (See gen:do_call/4 for an example of a receive statement that will be optimized.)

  Own Id: OTP-8623

- The functions file:advise/4 and file:datasync/1 have been added. (Thanks to Filipe David Manana.)

  Own Id: OTP-8637

- New NIF API functions: enif_make_atom_len, enif_make_existing_atom_len, enif_make_string_len, enif_get_atom_length, enif_get_list_length, enif_is_list, enif_is_tuple (by Tuncer Ayaz)

  Own Id: OTP-8640

- Support for using gcc's built-in functions for atomic memory access has been added. This functionallity will be used if available and no other native atomic implementation in ERTS is available.

  Own Id: OTP-8659

- The number of spinlocks used when implementing atomic fall-backs when no native atomic implementation is available has been increased from 16 to 1024.

  Own Id: OTP-8660

- Writer preferred pthread read/write locks has been enabled on Linux.

  Own Id: OTP-8661

- The runtime system will by default bind schedulers to logical processors using the default_bind bind type if the amount of schedulers are at least equal to the amount of logical processors configured, binding of schedulers is supported, and a CPU topology is available at startup.

  NOTE: If the Erlang runtime system is the only operating system process that binds threads to logical processors, this improves the performance of the runtime system. However, if other operating system processes (as for example another Erlang runtime system) also bind threads to logical processors, there might be a performance penalty instead. If this is the case you, are are advised to unbind the schedulers using the +sbtu command line argument, or by invoking erlang:system_flag(scheduler_bind_type, unbound).

  Own Id: OTP-8666

- The recently added BIFs erlang:min/2, erlang:max/2 and erlang:port_command/3 are now auto-imported (as they were originally intended to be). Due to the recent compiler change (OTP-8579), the only impact on old code defining it's own min/2, max/2 or port_command/3 functions will be a warning, the local functions will still be used. The warning can be removed by using -compile({no_auto_import,[min/2,max/2,port_command/3]}). in the source file.

  *** POTENTIAL INCOMPATIBILITY ***

  Own Id: OTP-8669 Aux Id: OTP-8579

- There is a new option 'exclusive' to file:open/2 that uses the OS O_EXCL flag where supported to open the file in exclusive mode.

  Own Id: OTP-8670

- Now, binary_to_term/2 is auto-imported. This will cause a compile warning if and only if a module has got a local function with that name.

  *** POTENTIAL INCOMPATIBILITY ***

  Own Id: OTP-8671

- Alignment of scheduler data and run queues were adjusted.

  Own Id: OTP-8673

- Call time breakpoint tracing

  - Introduce a call_time option to erlang:trace_pattern/3.This option enables call time breakpoint tracing on code that is executed by processes with call tracing enabled. Call time tracing stores the number of calls and the time spent of each function with this trace pattern enabled. The information can be retrieved with erlang:trace_info/2
  - Add a scheduler array for BpData. To solve the issue of multiple schedulers constantly updating the head pointer to the bp data wheel, each scheduler now has its own entrypoint to the wheel. This head pointer can be updated without a locking being taken.

  Teach call count tracing to use atomics

  - Call count previously used a global lock for accessing and writing its counter in the breakpoint. This is now changed to atomics instead.
  - The change will let call count tracing and cprof to scale better when increasing the number of schedulers.

  Own Id: OTP-8677

- eprof has been reimplemented with support in the Erlang virtual machine and is now both faster (i.e. slows down the code being measured less) and scales much better. In measurements we saw speed-ups compared to the old eprof ranging from 6 times (for sequential code that only uses one scheduler/core) up to 84 times (for parallel code that uses 8 cores).

  Note: The API for the eprof has been cleaned up and extended. See the documentation.

  *** POTENTIAL INCOMPATIBILITY ***

  Own Id: OTP-8706

### 1.14 Erts 5.7.5.2

#### Known Bugs and Problems

- Two bugs in gen_sctp has been corrected: getopts/setopts hence also send could only be called from socket owner, and options 'linger', 'rcvbuf' and 'sndbuf' was read from wrong protocol layer hence read wrong values by getopts.

  Own Id: OTP-9544

### 1.15 Erts 5.7.5.1

#### Fixed Bugs and Malfunctions

- Driver threads, such as async threads, using port data locks peeked at the port status field without proper locking when looking up the driver queue.

  Own Id: OTP-8475

- A call to the BIF unregister(RegName) when a port had the name RegName registered in the runtime system without SMP support caused a runtime system crash. (Thanks to Per Hedeland for the bugfix and test case.)

  Own Id: OTP-8487

- Fix memory management bug causing crash of non-SMP emulator with async threads enabled. The bug did first appear in R13B03.

  Own Id: OTP-8591 Aux Id: seq11554

### 1.16 Erts 5.7.5

#### Fixed Bugs and Malfunctions

- Fix binary_to_term crash on compressed term with corrupt size field.

  Own Id: OTP-8336

- Processes and/or ports could get stuck on a blocked scheduler when erlang:system_flag(multi_scheduling, block) was used.

  Processes and/or ports could get stuck on an offline scheduler when schedulers online were reduced using erlang:system_flag(schedulers_online, SchedulersOnline).

  Own Id: OTP-8342

- Building on Windows will now work if the paths to mc.exe and rc.exe contain spaces. The README.win32 file has been updated with some information about building using Visual Studio 2008. (Thanks to Andrew Thompson.)

  Own Id: OTP-8345

- EPMD now correctly handles the extra data field which can be given in the ALIVE2_REQ request and retrieved in the PORT2_RESP response. (Thanks to Klas Johansson.)

  Own Id: OTP-8361

- The configure test for reliable floating point exceptions has been update to work on modern versions of Mac OS X. (Thanks to Trannie Carter.)

  Own Id: OTP-8368

- ERTS makefiles used to detect the use of a gcc C compiler by checking if CC equaled gcc. That is, the makefiles failed to detect gcc C compilers with other command line names than gcc. `configure' now substitute GCC into the makefiles. If CC is a gcc C compiler, GCC will have the value yes. (Thanks to Jean-Sébastien Pédron)

  Own Id: OTP-8373

- ETS bug causing the memory counter from ets:info for ordered_set's to sometimes get out of synch and absurdly high.

  Own Id: OTP-8377 Aux Id: seq11442

- Immediately repeated multi-scheduling block/unblock cycles using erlang:system_flag(multi_scheduling, block | unblock) could deadlock the runtime system.

  Own Id: OTP-8386

- A number of bugs concerning re and unicode are corrected:

  re:compile no longer loses unicode option, which also fixes bug in re:split.

  re:replace now handles unicode charlist replacement argument

  re:replace now handles unicode RE charlist argument correctly

  re:replace now handles binary unicode output correctly when nothing is replaced.

  Most code, testcases and error isolation done by Rory Byrne.

  Own Id: OTP-8394

- The loading of native code was not properly atomic in the SMP emulator, which could cause crashes. Also a per-MFA information table for the native code has now been protected with a lock since it turns that it could be accessed concurrently in the SMP emulator. (Thanks to Mikael Pettersson.)

  Own Id: OTP-8397

- Fix processes in exiting status that are about to be scheduled, to not be allowed to garbage collect.

  Own Id: OTP-8420

- Removed bogus "\011" character sequence in documentation.

  Own Id: OTP-8422

- The resolver routines failed to look up the own node name as hostname, if the OS native resolver was erroneously configured, bug reported by Yogish Baliga, now fixed.

  The resolver routines now tries to parse the hostname as an IP string as most OS resolvers do, unless the native resolver is used.

  The DNS resolver inet_res and file resolver inet_hosts now do not read OS configuration files until they are needed. Since the native resolver is default, in most cases they are never needed.

  The DNS resolver's automatic updating of OS configuration file data (/etc/resolv.conf) now uses the 'domain' keyword as default search domain if there is no 'search' keyword.

  Own Id: OTP-8426 Aux Id: OTP-8381

- The re module: A regular expression with an option change at the start of a pattern that had top-level alternatives could cause overwriting and/or a crash. (Thanks to Michael Santos.)

  Own Id: OTP-8438

- Harmless buffer overflow by one byte in asn1 and ram_file_drv.

  Own Id: OTP-8451

#### Improvements and New Features

- Improved GC performance after BIF/NIF call when a lot of heap fragments was created. This will mainly benefit NIFs that return large compound terms.

  Own Id: OTP-8240

- Incompatible changes in the experimental NIF feature.

  - Changed the NIF function prototypes in order to allow more than 3 function arguments.
  - enif_get_data renamed as enif_priv_data.
  - enif_make_string got a third argument for character encoding.
  - The return value of erlang:load_nif/2 on error changed.

  Read more in the documentation of erl_nif and erlang:load_nif/2

  .

  *** POTENTIAL INCOMPATIBILITY ***

  Own Id: OTP-8304

- Cross compilation improvements and other build system improvements.

  Most notable:

  - Lots of cross compilation improvements. The old cross compilation support was more or less non-existing as well as broken. Please, note that the cross compilation support should still be considered as experimental. Also note that old cross compilation configurations cannot be used without modifications. For more information on cross compiling Erlang/OTP see the $ERL_TOP/INSTALL-CROSS.md file.
  - Support for staged install using DESTDIR. The old broken INSTALL_PREFIX has also been fixed. For more information see the $ERL_TOP/INSTALL.md file.
  - Documentation of the release target of the top Makefile. For more information see the $ERL_TOP/INSTALL.md file.
  - make install now by default creates relative symbolic links instead of absolute ones. For more information see the $ERL_TOP/INSTALL.md file.
  - $ERL_TOP/configure --help=recursive now works and prints help for all applications with configure scripts.
  - Doing make install, or make release directly after make all no longer triggers miscellaneous rebuilds.
  - Existing bootstrap system is now used when doing make install, or make release without a preceding make all.
  - The crypto and ssl applications use the same runtime library path when dynamically linking against libssl.so and libcrypto.so. The runtime library search path has also been extended.
  - The configure scripts of erl_interface and odbc now search for thread libraries and thread library quirks the same way as erts do.
  - The configure script of the odbc application now also looks for odbc libraries in lib64 and lib/64 directories when building on a 64-bit system.
  - The config.h.in file in the erl_interface application is now automatically generated in instead of statically updated which reduces the risk of configure tests without any effect.

  (Thanks to Henrik Riomar for suggestions and testing)

  (Thanks to Winston Smith for the AVR32-Linux cross configuration and testing)

  *** POTENTIAL INCOMPATIBILITY ***

  Own Id: OTP-8323

- NIF improvements:

  - Driver API for multi-threading made available for NIFs.
  - Support for mempory managed (garbage collected) resource objects. A way to pass "pointers" to native data structures between C and Erlang in a safe way.
  - Support for references, floats and term comparison.
  - Various new functions, like enif_inspect_iolist_as_binary, enif_make_sub_binary, enif_get_string, enif_get_atom, enif_make_tuple_from_array, enif_make_list_from_array, enif_make_existing_atom.

  Own Id: OTP-8335

- Minor alignment adjustments of scheduler specific data.

  Own Id: OTP-8341

- The documentation is now possible to build in an open source environment after a number of bugs are fixed and some features are added in the documentation build process.

  - The arity calculation is updated.

  - The module prefix used in the function names for bif's are removed in the generated links so the links will look like "http://www.erlang.org/doc/man/erlang.html#append_element-2" instead of "http://www.erlang.org/doc/man/erlang.html#erlang:append_element-2".

  - Enhanced the menu positioning in the html documentation when a new page is loaded.

  - A number of corrections in the generation of man pages (thanks to Sergei Golovan)

  - The legal notice is taken from the xml book file so OTP's build process can be used for non OTP applications.

  Own Id: OTP-8343

- There is new erlang:binary_to_term/2 BIF that takes an option list. The option safe can be used to prevent creation of resources that are not garbage collected (such as atoms). (Thanks to Jayson Vantuyl.)

  Own Id: OTP-8367

- The default settings for garbage collection of binaries has been adjusted to be less aggressive than in R13B03. It is now also possible configure the settings for binary GC. See the documentation for spawn_opt/2-5, erlang:system_info/1, erlang:system_flag/2, process_flag/2-3, erlang:trace/3, and the documenation for erl for the new command line options +hms and +hmbs.

  Own Id: OTP-8370

- A bug causing memory corruption in re:run() has been corrected. (Thanks to Yamashina Hio.)

  Own Id: OTP-8375

- The -Werror option for erlc and the compiler option warnings_as_errors will cause warnings to be treated as errors. (Thanks to Christopher Faulet.)

  Own Id: OTP-8382

- Explicit top directories in archive files are now optional.

  For example, if an archive (app-vsn.ez) just contains an app-vsn/ebin/mod.beam file, the file info for the app-vsn and app-vsn/ebin directories are faked using the file info from the archive file as origin. The virtual direcories can also be listed. For short, the top directories are virtual if they does not exist.

  Own Id: OTP-8387

- An unnecessary lock operation in os:timestamp/0 has been eliminated, making it slightly more efficient. (Thanks to Jonas Falkevik and Tuncer Ayaz.)

  Own Id: OTP-8390

- There is a new +t emulator option for changing the maximum number of atoms. (Thanks to Julien Barbot.)

  Own Id: OTP-8405

- Fixed numerous compiler warnings generated by gcc 4.4.1 and tile-cc 2.0.1.78377 when compiling the runtime system.

  Own Id: OTP-8412

- configure learned the option --enable-m32-build to force the building of a 32-bit run-time on systems where the default C compiler generates 64-bit executables by default.

  Own Id: OTP-8415

- HiPE now works in the 64-bit emulator on Mac OS X. (Thanks to Geoff Cant.)

  Own Id: OTP-8416

- Improved handling of symbolic links to escripts

  Own Id: OTP-8417

- Add lock profiling tool.

  The Lock profiling tool, lcnt, can make use of the internal lock statistics when the runtime system is built with this feature enabled.

  This provides a mechanism to examine potential lock bottlenecks within the runtime itself.

  - Add erts_debug:lock_counters({copy_save, bool()}). This option enables or disables statistics saving for destroyed processes and ets-tables. Enabling this might consume a lot of memory.

  - Add id-numbering for lock classes which is otherwise undefined.

  Own Id: OTP-8424

- Removed spurious options to the emulator from escript.

  Own Id: OTP-8427

- Minor documentation fixes. Mainly anchor adjustments.

  Own Id: OTP-8457

### 1.17 Erts 5.7.4

#### Fixed Bugs and Malfunctions

- An insufficient stack allocation was made when reading CPU information on BSD operating systems. (Thanks Michael Turner and Akira Kitada)

  Own Id: OTP-8207

- A bug when supplying an argument without a dash directly after the program name when starting erlang could prevent distribution to start. This is now corrected.

  Own Id: OTP-8209

- A ticker process could potentially be blocked indefinitely trying to send a tick to a node not responding. If this happened, the connection would not be brought down as it should.

  Own Id: OTP-8218

- Using certain firewalls (i.e. MS IAS Client and certain versions of COMODO) could expose an undocumented behaviour in the Win32 socket interface causing the name resolution calls to hang infinitely. This is now worked around by adding possibilities for port programs under Windows to use overlapped I/O on their standard input/output file handles.

  Own Id: OTP-8230

- Fixed bug on ETS tables with write_concurrency. The emulator could crash when doing a select or match with a bound key without finding any object.

  Own Id: OTP-8242

- The information-request / information-response, and group-leader-change-request / group-leader-changed-response signal pairs described below did not always adhere to the signal order guarantees of Erlang's signal model in the runtime system with SMP support. These signals could for example sometimes pass exit signals.

  The following BIFs behaviors can be modeled as if an asynchronous information-request signal is sent to Pid. If Pid is alive, it responds with an asynchronous information-response signal; otherwise, the runtime system responds with a no-such-process signal. When the response is received, the caller transforms it into the result of the BIF.

  - is_process_alive(Pid)
  - erlang:process_display(Pid, Type)
  - process_info(Pid)
  - process_info(Pid, ItemSpec)

  When Pid resides on the same node as the caller of group_leader(GroupLeader, Pid), the group_leader/2 BIFs behavior can be modeled as if an asynchronous group-leader-change-request signal is sent to Pid. If Pid is alive, it responds with an asynchronous group-leader-changed-response signal; otherwise, the runtime system responds with a no-such-process signal. When the response is received, the caller transforms it into the result of the BIF. The distributed case which only consists of an asynchronous group-leader-change-request signal and no response is not effected.

  Own Id: OTP-8245

- Errors in the system_profile documentation has been corrected.

  Own Id: OTP-8257

- Low watermark socket option modified high watermark instead of low watermark in the inet_driver. (Thanks to Feng Yu and Tuncer Ayaz)

  Own Id: OTP-8279

- A race condition could cause the runtime system with SMP support to end up in a completely unresponsive state.

  Own Id: OTP-8297

#### Improvements and New Features

- The use of pthread_cond_timedwait() have been completely removed from the runtime system. This since its behavior is unpredictable when the system clock is suddenly changed. The previous use of it was harmless.

  Own Id: OTP-8193

- The documentation is now built with open source tools (xsltproc and fop) that exists on most platforms. One visible change is that the frames are removed.

  Own Id: OTP-8201

- A new garbage collecting strategy for binaries which is more aggressive than the previous implementation. Binaries now has a virtual binary heap tied to each process. When binaries are created or received to a process it will check if the heap limit has been reached and if a reclaim should be done. This imitates the behavior of ordinary Erlang terms. The virtual heaps are grown and shrunk like ordinary heaps. This will lessen the memory footprint of binaries in a system.

  Own Id: OTP-8202

- The ErlDrvTermData term types used by driver_output_term() and driver_send_term() have been extended with the term types ERL_DRV_INT64, and ERL_DRV_UINT64 for passing 64-bit integers. Also the 64-bit integer data types ErlDrvSInt64 and ErlDrvUInt64 have been introduced.

  For more information see the erl_driver(3) documentation.

  Own Id: OTP-8205

- [escript] The restriction that the first line in escripts must begin with #! has been removed.

  [escript] Some command line options to the escript executable has now been documented. For example you can run an escript in the debugger by just adding a command line option.

  [escript] The documentation of the escript header syntax has been clarified. For example the header is optional. This means that it is possible to directly "execute" .erl, .beam and.zip files.

  Own Id: OTP-8215

- The instruction for building OTP on Windows was outdated and incomplete, the document is updated.

  Also the otp_build script required windows drives to show up in Cygwin using the /cygdrive prefix. That requirement is now removed.

  Own Id: OTP-8219

- A module can have native implemented functions (NIFs) that are dynamically loaded by calling erlang:load_nif/2. This is an experimental feature that is not yet intended for production systems. It is released with intention to get some early feedback on the interfaces before they are carved in stone.

  Own Id: OTP-8220

- The float/1 BIF would always force a garbage collection. The BIFs size/1, byte_size/1, bit_size/1, abs/1, and round/1 would force a garbage-collection if the result was not a sufficiently small integer.

  Own Id: OTP-8221

- The erlang:port_command/3 BIF has been added. erlang:port_command/3 is currently not auto imported, but it is planned to be auto imported in OTP R14. For more information see the erlang(3) documentation.

  Own Id: OTP-8225

- 'configure --enable-darwin-64bit' would fail if Snow Leopard had been booted with the 64-bit kernel. (Thanks to Ryan M. Graham.)

  Own Id: OTP-8236

### 1.18 Erts 5.7.3

#### Fixed Bugs and Malfunctions

- On Windows, open_port({spawn,Command},Opts) could not run executables with spaces in the path or filename, regardless of quoting efforts. While open_port({spawn_executable,Exec},Opts) can run any executable, it was still impossible to use 'spawn' to do the same thing. This is now corrected.

  Own Id: OTP-8055

- The scheduler bind type processor_spread spread schedulers too much on large NUMA systems.

  The new scheduler bind type spread spreads schedulers as much as possible, and behaves as processor_spread previously did. For more information see the documentation of the +sbt command line argument in the erl(1) documentation, and the documentation of erlang:system_flag(scheduler_bind_type, SchedulerBindType).

  Own Id: OTP-8063

- Automatically detected CPU topology on Linux system could erroneously contain logical processors with -1 as identifiers. This happened when sysconf(_SC_NPROCESSORS_CONF) returned a value larger than the amount of logical processors found.

  Own Id: OTP-8064

- When the minimal term [] (end of list) was sent as the complete message to a process on another node, and received there, it could not be decoded. This bug is now corrected. Fortunately [] is uncommon as the complete message in real applications but it is a serious bug anyway.

  Own Id: OTP-8092

- A bug when the floating point exception pointer was not initialized has been corrected. It manifested itself on CentOS 5.1 sometimes when a floating point value was sent to a remote node. Bug reported and patch suggested by David Reiss, confirmed by Mikael Pettersson.

  Some build problems on IRIX was also corrected. Problem reported by Patrick Baggett, patch by Mikael Pettersson.

  Own Id: OTP-8095

- A terminating process could erroneously unregister a name for another process. This could occur under the following conditions: The name of the terminating process was unregistered and then registered for another process simultaneously as the process that first had the name was terminating.

  Own Id: OTP-8099 Aux Id: seq11344

- Running erlc in a very deep directory (with a path length of more 256 or more characters) would cause the emulator to crash in a call to list_to_atom/1. (Thanks to Chris Newcombe.)

  Own Id: OTP-8124

- A deadlock of the runtime system could occur when unregistering the name of a port.

  Own Id: OTP-8145

- Makefile.in has been updated to use the LDFLAGS environment variable (if set). (Thanks to Davide Pesavento.)

  Own Id: OTP-8157

- The pthread rwlock implemention on Linux could cause starvation of writers. We, therefore, now use our own rwlock implementation on Linux.

  Own Id: OTP-8158

- Open source Erlang builds are updated to work well on Snow Leopard (MacOS X 10.6)

  Own Id: OTP-8168

- A call to erlang:system_info(schedulers_online) could end up in an infinite loop. This happened if the amount of schedulers was larger than one, the amount of schedulers online was one, and someone was blocking multi-scheduling.

  Own Id: OTP-8169

- An error in erlang:system_profile/2 could cause timestamped messages to arrive out of order in the SMP case. This has now been fixed.

  Own Id: OTP-8171

- binary_to_atom/2 and binary_to_existing_atom/2 would leak memory if the binary contained unaligned data.

  Own Id: OTP-8192

- The async thread pool in the runtime system without SMP support used a memory allocator that was not thread safe for async jobs.

  Own Id: OTP-8194

#### Improvements and New Features

- Processor internal NUMA nodes are now supported in the ERTS internal CPU topology representation. For more information see the documentation of the +sct command line argument in the erl(1) documentation, and the documentation of erlang:system_info(cpu_topology).

  Own Id: OTP-8041

- Documentation for ets improved about concurrency.

  Own Id: OTP-8050

- Emulator flags in an escript were earlier inherited to emulators started from from the emulator running the escript. For example when an escript invoked os:cmd("erl"), the new emulator were given erroneous emulator flags. This bug has now been fixed

  Escript filenames may now contain dots.

  Own Id: OTP-8060

- Made some BIFs non-recursive (relational operators,hash and phash) to limit internal stack usage.

  Own Id: OTP-8065

- Fixed Windows specific bug in erl_prim_loader. Now it handles the root directory (e.g. c:/) better. This bug affected the directory listing in the debugger.

  Own Id: OTP-8080

- A TCP socket with option {packet,4} could crash the emulator if it received a packet header with a very large size value (>2Gb). The same bug caused erlang:decode_packet/3 to return faulty values. (Thanks to Georgos Seganos.)

  Own Id: OTP-8102

- The maximum size of the export table has been raised from 65536 to 524288 entries.

  Own Id: OTP-8104 Aux Id: seq11345

- The file module has now a read_line/1 function similar to the io:get_line/2, but with byte oriented semantics. The function file:read_line/1 works for raw files as well, but for good performance it is recommended to use it together with the 'read_ahead' option for raw file access.

  Own Id: OTP-8108

- Fixed bug causing emulator crash when reading a term in external format containing a corrupt list with a negative length.

  Own Id: OTP-8117

- New emulator flag +sss, to set stack size of scheduler threads.

  Own Id: OTP-8119

- The Windows utility Erlsrv, run in interactive mode now accepts options for registering internal service name and description field of Windows registry database.

  Own Id: OTP-8132

- erlang:demonitor(Mon, [flush]) has been optimized. Previously it always searched the message queue of the caller for a 'DOWN' message. Current implementation only search the message queue when necessary. It is quite common that the search is not necessary.

  A new option info has been added to erlang:demonitor/2. For more information see the erlang(3) documentation.

  Own Id: OTP-8143

- I/O tasks could unnecessarily be rescheduled. This was harmless, but not useful work.

  Own Id: OTP-8148

- Minor improvements of erlang:memory/[1,2].

  Own Id: OTP-8152

- New configuration option to enable use of shared zlib.

  Own Id: OTP-8155

- Fixed smp bug in ETS that could cause emulator crash when table with more than 1000 objects accessed by several processes, including calls to variants of select or match combined with concurrent object deletion.

  Own Id: OTP-8166 Aux Id: seq11392

- The code path interpretation is now more relaxed. The flag -code_path_choice now defaults to relaxed instead of strict. See the documentation of code and init for more info.

  Own Id: OTP-8170

- Load balancing of run queues and check for I/O are triggered more often than before in situations where processes are scheduled often but are doing very little work each time they execute.

  Own Id: OTP-8172

- Call tracing binary comprehensions would cause an emulator crash. (Thanks to Paul Mineiro.)

  Own Id: OTP-8179

- binary_to_term/1 would crash the emulator instead of generating a badarg exception when given certain invalid terms. (Thanks to Scott Lystig Fritchie.)

  Own Id: OTP-8180

### 1.19 Erts 5.7.2

#### Fixed Bugs and Malfunctions

- Crash dumps should now cause less problems for the crashdump_viewer application. (For processes where arity was non-zero, the arguments are now longer printed - they used to be printed in a format that was not parseable.)

  Own Id: OTP-7472 Aux Id: seq11019, 11292

- Processes could potentially get stuck on an offline scheduler.

  Own Id: OTP-7990

- binary_to_atom/2 and binary_to_existing_atom/2 could leak memory if they caused a badarg exception.

  Own Id: OTP-7997

- A process could under very rare circumstances erroneously be resumed.

  Own Id: OTP-8000

- Load balancing between schedulers could under rare circumstances cause an emulator crash.

  Own Id: OTP-8008

- erlang:memory(processes_used) always returned 0 instead of the correct value. (Thanks to Geoff Cant)

  Own Id: OTP-8022

#### Improvements and New Features

- Major improvements of the Erlang distribution for Erlang runtime systems with SMP support. Previously distribution port locks were heavily contended, and all encoding and decoding for a specific distribution channel had to be done in sequence. Lock contention due to the distribution is now negligible and both encoding and decoding of Erlang messages can be done in parallel.

  The old atom cache protocol used by the Erlang distribution has been dropped since it effectively prevented all parallel encoding and decoding of messages passed over the same distribution channel.

  A new atom cache protocol has been introduced which isolates atom cache accesses and makes parallel encoding and decoding of messages passed over the same distribution channel possible. The new atom cache protocol also use an atom cache size 8 times larger than before. The new atom cache protocol is documented in the ERTS users guide.

  Erlang messages received via the distribution are now decoded by the receiving Erlang processes without holding any distribution channel specific locks. Erlang messages and signals sent over the distribution are as before encoded by the sending Erlang process, but now without holding any distribution channel specific locks during the encoding. That is, both encoding and decoding can be and are done in parallel regardless of distribution channel used.

  The part that cannot be parallelized is the atom cache updates. Atom cache updates are therefore now scheduled on the distribution port. Since it is only one entity per distribution channel doing this work there is no lock contention due to the atom cache updates.

  The new runtime system does not understand the old atom cache protocol. New and old runtime systems can however still communicate, but no atom cache will be used.

  Own Id: OTP-7774

- Fixed a bug that caused error logging from driver_select sometimes with additional symptoms such as failing IP communications or even an emulator crash.

  Own Id: OTP-7898 Aux Id: seq11304

- Improved SMP concurrency for ETS tables. Several mutating operations can now be performed truly concurrent on different records of the same table. To support this, the table has to be created with option write_concurrency, as it is achieved at the expense of some execution and memory overhead. ets:select and select_count has also been improved for all tables to not acquire exclusive table lock during the iteration.

  Own Id: OTP-7922

- erl (that is erl.exe and dyn_erl) and erlexec has been made more dynamic so no hard coded paths needs to added at installation time to erl (that is erl.ini and erl). Reltool will make use of this in a future release.

  Own Id: OTP-7952

- Added functionality to get higher resolution timestamp from system. The erlang:now function returns a timestamp that's not always consistent with the actual operating system time (due to resilience against large time changes in the operating system). The function os:timestamp/0 is added to get a similar timestamp as the one being returned by erlang:now, but untouched by Erlangs time correcting and smoothing algorithms. The timestamp returned by os:timestamp is always consistent with the operating systems view of time, like the calendar functions for getting wall clock time, but with higher resolution. Example of usage can be found in the os manual page.

  Own Id: OTP-7971

- Two new options are added to open_port - spawn_executable which runs external executables in a controlled way, and spawn_driver which only opens port to loaded Erlang drivers. See the erlang manual page for details.

  Own Id: OTP-7995

- New functionality in ETS to transfer the ownership of a table. A table can either change owner be declaring an "heir", another process that will inherit the table if the owner terminates. A table can also change owner by calling a new function ets:give_away.

  Own Id: OTP-8006

- Updates to Tilera build environment.

  Own Id: OTP-8009

- A stack trace was unnecessarily saved during process termination.

  Own Id: OTP-8014

- User defined CPU topology and scheduler bind type can now be set from the command line when starting an emulator. For more information see the documentation of the +sct, and the +sbt emulator flags in the erl(1) documentation.

  The CPU topologies returned from erlang:system_info/1 and erlang:system_flag/2 now always contain the processor level, also when not strictly necessary.

  Own Id: OTP-8030

- Various fixes in ETS: ets:first could return a deleted key in a fixated table. ets:lookup could return objects out of order if a deleted object was re-inserted into a fixed bag. ets:delete_object could fail to delete duplicate objects in a duplicate_bag.

  Own Id: OTP-8040

### 1.20 Erts 5.7.1

#### Fixed Bugs and Malfunctions

- Fixed a bug on Windows that could make gen_tcp:send hang trying to send an iolist of more than 16 binaries.

  Own Id: OTP-7816

- The runtime system could under rare circumstances crash during load balancing.

  Own Id: OTP-7908 Aux Id: otp-7500

- run_erl uses fallback if Unix98 pseudo-terminal is not present on host.

  Own Id: OTP-7916 Aux Id: seq11249

- A message buffer memory leak in the runtime system without smp support has been fixed.

  Own Id: OTP-7941

- Attempting to append a binary of 16Mb or greater to another binary using the bit syntax would cause a system_limit exception. There was also several cases when constructing binaries when a badarg exception was generated when it should have been system_limit.

  Own Id: OTP-7942

- The runtime system with SMP support failed to terminate the caller of link(RemotePid) properly, if RemotePid was the pid of a process on an unreachable node. The calling process was in this case marked as exiting, but never terminated.

  Own Id: OTP-7946

#### Improvements and New Features

- Rudimentary support for cross compiling is added to the source release. The support is still in its infancy and has only been used to cross compile on Linux for a different cpu architecture and a different Linux version, but should be extendible to support other platforms as well. The cross configuration files with examples are placed in $ERL_TOP/xcomp/. View README.xcomp and run $ERL_TOP/otp_build -help for further information.

  Own Id: OTP-7854

- The escape sequence \{ which was given a new interpretation in R13A has retained its old meaning (the ASCII code for {), which means that codes greater than 255 have to be stated using hexadecimal characters (for example, \x{AAA}). The escape sequence \xH where H is a hexadecimal character followed by something else but a hexadecimal character is no longer valid (incompatibility with R13A). Character codes less than 256 can be stated using two hexadecimal characters (for example, \x0D).

  Own Id: OTP-7891 Aux Id: OTP-7855

- The term_to_binary/1 BIF used to be implemented with recursive C code, which could cause the Erlang emulator to terminate because of a stack overflow.

  Also fixed some minor issues in term_to_binary/1 and binary_to_term/1 pointed out by Matthew Dempsky.

  Own Id: OTP-7894

- Several glitches and performance issues in the Unicode and I/O-system implementation of R13A have been corrected.

  Own Id: OTP-7896 Aux Id: OTP-7648 OTP-7887

- Minor documentation improvements of the scheduler_bind_type argument of erlang:system_flag/2, and the scheduler_bind_type, and the scheduler_bindings arguments of erlang:system_info/1.

  Own Id: OTP-7901 Aux Id: OTP-7777

- There is a new BIF erlang:make_tuple/3.

  Own Id: OTP-7913

### 1.21 Erts 5.7

#### Fixed Bugs and Malfunctions

- OpenSource:

  FreeBSD leap-seconds are handled according to patch submitted by OpenSource user Kenji Rikitake. No test case covers this functionality (unsupported platform).

  Own Id: OTP-7609

- A corrected bug in ets for bag and duplicate_bag. A delete/2 or lookup_element/3 could miss objects in a fixed table if one or more objects with the same key had already been deleted.

  Own Id: OTP-7665

- A new driver call-back stop_select is introduced to allow drivers to de-select and then close a file descriptor in a safe way in a SMP emulator. The old way was not strictly according to posix standard and could in some rare cases lead to unexpected behavior. A new flag ERL_DRV_USE can be passed to driver_select() to tell it that the descriptor should be closed. stop_select is then called when it is safe to do so. Old drivers will however still work as before.

  Own Id: OTP-7670

- A bug fixed for TCP sockets with option {packet,http}. An HTTP request with an absolute URI was returned with a corrupt path string. This bug did only exist in R12B-4 and R12B-5.

  Own Id: OTP-7682 Aux Id: OTP-7647

- run_erl did in some cases fail to extract control sequences from to_erl (like: winsize=X,Y) and did instead send them to be interpreted by the erlang shell.

  Own Id: OTP-7688

- A bug in the installer on Windows not updating file associations properly is now corrected.

  Own Id: OTP-7746

- More space than necessary could be allocated in binaries when appending to a binary (also in a binary comprehension) and the data appended did not consist of wholes bytes (e.g. 13 bits).

  Own Id: OTP-7747

- The gen_sctp option sctp_peer_addr_params, #sctp_paddrparams{address={IP,Port} was erroneously decoded in the inet driver. This bug has now been corrected.

  Own Id: OTP-7755

- Outstanding async driver jobs leaked memory if the issuing port died before the async jobs completed.

  Own Id: OTP-7784

- A bug in the dynamic library loading affecting, among others, OpenSolaris is now corrected. (Thanks to Paul Fisher.)

  Own Id: OTP-7796

- run_erl compile errors fixed for FreeBSD

  Own Id: OTP-7817

- A bug in the inet driver for SCTP on Solaris showing for e.g gen_sctp:abort/1 and gen_sctp:eof/1 has been corrected. Patch suggestion by Simon Cornish.

  Own Id: OTP-7866

#### Improvements and New Features

- The order of objects visited in select for ordered_set is now documented.

  Own Id: OTP-7339

- The runtime system with SMP support now uses multiple, scheduler specific run queues, instead of one globally shared run queue.

  The lock protecting the shared run queue was heavily contended, and the shared run queue also caused Erlang processes to randomly migrate between schedulers with negative cache effects as a result.

  With the current scheduler specific run queue solution, lock contention due to run queue protection has been reduced, and Erlang processes are only migrated when needed to balance the load between the schedulers. The reduced amount of migration also reduce lock contention on locks protecting the scheduler specific instances of the erts internal memory allocators.

  The scheduler specific run queues are also a necessity for a lot of future planned NUMA (Non-Uniform Memory Access) specific optimizations.

  Own Id: OTP-7500

- Support for Unicode is implemented as described in EEP10. Formatting and reading of unicode data both from terminals and files is supported by the io and io_lib modules. Files can be opened in modes with automatic translation to and from different unicode formats. The module 'unicode' contains functions for conversion between external and internal unicode formats and the re module has support for unicode data. There is also language syntax for specifying string and character data beyond the ISO-latin-1 range.

  The interactive shell will support input and output of unicode characters when the terminal and operating system supports it.

  Please see the EEP and the io/io_lib manual pages as well as the stdlib users guide for details.

  I/O-protocol incompatibilities:

  The io_protocol between io_Server and client is updated to handle protocol data in unicode formats. The updated protocol is now documented. The specification resides in the stdlib users manual, which is a new part of the manual.

  io module incompatibilities:

  The io:put_chars, io:get_chars and io:get_line all handle and return unicode data. In the case where binaries can be provided (as to io:put_chars), they shall be encoded in UTF-8. When binaries are returned (as by io:get_line/get_chars when the io_server is set in binary mode) the returned data is also always encoded as UTF-8. The file module however still returns byte-oriented data, why file:read can be used instead of io:get_chars to read binary data in ISO-latin-1.

  io_lib module incompatibilities:

  io_lib:format can, given new format directives (i.e "~ts" and "~tc"), return lists containing integers larger than 255.

  *** POTENTIAL INCOMPATIBILITY ***

  Own Id: OTP-7648 Aux Id: OTP-7580 OTP-7514 OTP-7494 OTP-7443 OTP-7181 EEP10 EEP11

- The format of the string returned by erlang:system_info(system_version) (as well as the first message when Erlang is started) has changed. The string now contains the both the OTP version number as well as the erts version number.

  Own Id: OTP-7649

- Message passing has been further optimized for parallel execution. Serial message passing is slightly more expensive than before, but parallel send to a common receiver is much cheaper.

  Own Id: OTP-7659

- Lock contention on the atom table lock when decoding Erlang terms on the external format has been drastically reduced.

  Own Id: OTP-7660

- The undocumented, unsupported, and deprecated guard BIF is_constant/1 has been removed.

  *** INCOMPATIBILITY with R12B ***

  Own Id: OTP-7673

- The Erlang process lock implementation has been improved by Mat Hostetter at Tilera Corporation.

  Own Id: OTP-7692

- A {nodedown, Node} message passed by the net_kernel:monitor_nodes/X functionality is now guaranteed to be sent after Node has been removed from the result returned by erlang:nodes/Y.

  Own Id: OTP-7725

- The short-circuit operators andalso and orelse no longer guarantees that their second argument is either true or false. As a consequence, andalso/orelse are now tail-recursive.

  *** POTENTIAL INCOMPATIBILITY ***

  Own Id: OTP-7748

- A new BIF, lists:keyfind/3, has been added. It works like lists:keysearch/3 except that it does not wrap the returned tuple in a value tuple in case of success. (Thanks to James Hague for suggesting this function.)

  Own Id: OTP-7752

- Optimization for drivers by creating small binaries direct on process heap.

  Own Id: OTP-7762

- I bsl N could cause the Erlang virtual machine to run of memory instead generating a system_limit if N was absurdly huge. (Thanks to Daniel Hedlund.)

  There would always be a garbage collection when evaluating I bsl N or I bsr N if I was a bignum.

  If I is an integer and N a bignum, I bsl N will now cause the correct system_limit exception instead of bad_arith as in earlier releases.

  If I is an integer and N a bignum, I bsr N will return either 0 or -1 depending on the sign of I instead of causing a bad_arith exception as in earlier releases.

  Own Id: OTP-7764

- Scheduler threads can now be bound to logical processors on newer Linux and Solaris systems. More systems will be supported in the future.

  In some cases performance has increased drastically when binding schedulers. Schedulers are not bound by default, though. This since it might cause a performance degradation if multiple programs have bound to processors, e.g. multiple Erlang runtime systems. For more information see the documentation of erlang:system_flag/2.

  In order to bind scheduler threads the CPU topology need to be known. On some newer Linux and Solaris systems the runtime system automatically detects the CPU topology. If the emulator isn't able to automatically detect the CPU topology, the CPU topology can be defined. For more information see the documentation of erlang:system_flag/2.

  Own Id: OTP-7777

- The compiler will refuse to a compile file where the module name in the file differs from the output file name.

  When compiling using erlc, the current working directory will no be included in the code path (unless explicitly added using "-pa .").

  *** POTENTIAL INCOMPATIBILITY ***

  Own Id: OTP-7793

- The BIFs atom_to_binary/2, binary_to_atom/2, and binary_to_existing_atom/2 have been added.

  Own Id: OTP-7804

- The amount of schedulers online can now be changed during operation. The amount of schedulers online defaults to the same amount as available logical processors. For more information see the documentation of erlang:system_flag/2 and erl.

  Own Id: OTP-7811

- The deprecated functions erlang:fault/1, erlang:fault/2, and file:rawopen/2 have been removed.

  *** POTENTIAL INCOMPATIBILITY ***

  Own Id: OTP-7812

- Erts internal dynamically allocated process and port specific data for rarely used data. This is used to reduce memory usage of processes and ports that do not use specific functionality. More functionality will be moved to process and port specific data in future releases.

  Own Id: OTP-7818

- New packet type http_bin for gen_tcp sockets and erlang:decode_packet. It works like http except that strings are returned as binaries instead of lists.

  Own Id: OTP-7821

- The obsolete wd_keeper program for embedded Solaris systems has been removed.

  Own Id: OTP-7822

- Nodes belonging to different independent clusters can now co-exist on the same host with the help of a new environment variable setting ERL_EPMD_PORT.

  Own Id: OTP-7826

- There are new functions erlang:min/2 and erlang:max/2 to calculate the minimum and maximum of two terms, respectively. Note that the functions are not auto-imported, so they need to be imported explicitly or the erlang prefix must be used when calling them.

  Own Id: OTP-7841

- The copyright notices have been updated.

  Own Id: OTP-7851

- Enhanced build environment for cross compilation to Tilera Tile architecture.

  Support for native ethread atomics on Tilera Tile64/TilePro (Thanks to Tilera Corporation).

  Own Id: OTP-7852

- The escape sequences \x and \{ have been assigned new interpretations (they used to return the ASCII code for x and { respectively). One or more octal characters inside curly brackets after a leading backslash is from now on an alternative to the existing syntax \NNN, but can also be used for codes greater than 255. In a similar fashion, one or more hexadecimal characters can be put inside curly brackets after a leading \x. Furthermore, the escape sequences \xH and \xHH, where N is a hexadecimal character, can be used for codes less than 256.

  NOTE: These new escape sequences are still considered experimental and may be changed in the R13B release.

  *** POTENTIAL INCOMPATIBILITY ***

  Own Id: OTP-7855

- The PCRE library's exported function names are now prefixed with erts_ in the erlang emulator to avoid clashes with dynamically loaded drivers.

  Own Id: OTP-7861

- A runtime system with SMP support will now be built by default on most platforms if a usable posix thread library or native windows threads are found.

  For more information see the top README file.

  Own Id: OTP-7872

### 1.22 Erts 5.6.5.1

#### Fixed Bugs and Malfunctions

- A corrected bug in ets for bag and duplicate_bag. A delete/2 or lookup_element/3 could miss objects in a fixed table if one or more objects with the same key had already been deleted.

  Own Id: OTP-7665

- A bug fixed for TCP sockets with option {packet,http}. An HTTP request with an absolute URI was returned with a corrupt path string. This bug did only exist in R12B-4 and R12B-5.

  Own Id: OTP-7682 Aux Id: OTP-7647

- Calling gen_tcp:send() from several processes on socket with option send_timeout could lead to much longer timeout than specified. The solution is a new socket option {send_timeout_close,true} that will do automatic close on timeout. Subsequent calls to send will then immediately fail due to the closed connection.

  Own Id: OTP-7731 Aux Id: seq11161

- A process being garbage collected via the garbage_collect/1 BIF or the check_process_code/2 BIF didn't handle message receive and resume correctly during the garbage collect. When this occurred, the process returned to the state it had before the garbage collect instead of entering the new state.

  Own Id: OTP-7738

### 1.23 Erts 5.6.5

#### Fixed Bugs and Malfunctions

- A bug in inet_drv concerning gen_tcp:connect has been corrected. A connect towards a non-open port through open firewalls could sometimes erroneously be successful. Any subsequent operation would fail, though.

  Own Id: OTP-6542

- Floating point arithmetics in drivers could cause a runtime system crash and/or unexpected results on runtime systems with floating point exceptions enabled. Floating point exceptions are disabled unless explicitly enabled or if hipe is enabled.

  Own Id: OTP-7237

- A bug when many sockets got signalled simultaneously causing the emulator to panic with the message "Inconsistent, why isnt io reported?" is now corrected.

  Own Id: OTP-7420

- Starting erl with option "-detached" now disconnects correctly from terminal session on Unix.

  Own Id: OTP-7461

- Mended gdb etp-commands for ETS access.

  Own Id: OTP-7538

- erlang:decode_packet/3 allows white space between HTTP header tag and colon according to RFC2616.

  Own Id: OTP-7543

- An emulator compiled for SCTP now starts even if the dynamic libraries are not present. The SCTP driver is then of course not loaded.

  Own Id: OTP-7551

- To build on Mac OS X, 10.3.0 or later is now required because of fixes for two problems:

  There would be a resource leak when erl_ddl attempted to unload a driver. This problem has been corrected by using dlopen() (which works on all modern Unix-like platforms) instead of the Mac OS X specific API calls.

  Signal handling in the run-time system for HiPE has been updated to work on later versions of Mac OS X than 10.2.x. Therefore, --enable-hipe now works on Mac OS X with Intel CPUs.

  Thanks to Geoff Cant for the patches.

  Own Id: OTP-7562

- Corrected some information about the protocol between EPMD and Erlang nodes. (Thanks to Michael Regen.)

  Own Id: OTP-7594

- When using erlang:system_monitor(Pid,{long_gc,Time}), and the GC time exceeded 1 second, it sometimes erroneously showed up as about 4300 seconds. (This bug was corrected in R9C, but re-introduced in R12B.) (Thanks to Chris Newcombe.)

  Own Id: OTP-7622 Aux Id: OTP-4903, seq8379

#### Improvements and New Features

- The driver entry of a dynamically loaded driver is now copied when loaded which enables some internal optimizations. Note that drivers that modify the driver entry during execution will not work anymore. Such a miss-use of the driver interface is however not supported.

  Own Id: OTP-6900

- The split function is now added to the re library. Exceptions and errors from both run, replace and split are made more consistent.

  Own Id: OTP-7514 Aux Id: OTP-7494

- Fixed harmless compiler warnings when building the emulator and minor build changes in order to avoid unnecessary rebuilds.

  Own Id: OTP-7530

- There is now experimental support for loading of code from archive files. See the documentation of code, init, erl_prim_loader and escript for more info.

  The error handling of escripts has been improved.

  An escript may now set explicit arguments to the emulator, such as -smp enabled.

  An escript may now contain a precompiled beam file.

  An escript may now contain an archive file containing one or more applications (experimental).

  The internal module code_aux has been removed.

  Own Id: OTP-7548 Aux Id: otp-6622

- The reallocation functionality part of the ERTS internal memory allocators, now consider current block in combination with surrounding free blocks as an alternative location for a reallocation.

  Own Id: OTP-7555

- There could remain false references from a process to a module that has been called earlier, so that the process would be killed if the module was reloaded. (Thanks to Richard Carlsson.)

  Also, the fix for this bug also made it possible to make stack backtraces (as returned from erlang:get_stacktrace/0 and other functions) more correct in that the immediate caller is always included in the stack backtrace (it could sometimes be missing).

  Own Id: OTP-7559

- Improved locking in IO-handling for better smp performance.

  Own Id: OTP-7560

- Improved BIF rescheduling functionality.

  Own Id: OTP-7587

- Loading a module compiled with Erlang/OTP R9C and calling module_info/0 in the module would crash the emulator. The emulator now refuses to load any module compiled with R9C or earlier. (Note: only trivial modules compiled with R10B or earlier could be loaded anyway.) (Thanks to Martin Kjellin.)

  Own Id: OTP-7590

### 1.24 Erts 5.6.4.2

#### Fixed Bugs and Malfunctions

- A process calling one of the following BIFs could under very rare conditions deadlock in the runtime system with SMP support: check_process_code/2, garbage_collect/1, process_info/[1,2], system_flag/2, and erlang:suspend_process/[1,2].

  Own Id: OTP-7582

- A couple of statistics variables were not managed in a thread safe manner in the runtime system with SMP support.

  Own Id: OTP-7583

- An extremely rare race condition when terminating a process could potentially cause a runtime system crash.

  Own Id: OTP-7584

- Under certain conditions and when using run_erl/to_erl, the terminal Erlang driver (ttsl_drv) could crash the emulator by doing a division by zero due to incorrect handling of terminals reporting a zero width. For terminals reporting zero width, the driver now fallbacks to a default width of 80 and a default height of 24 (vt100), as a fallback behaviour. This fixes the crashes and also makes output on "dumb" terminals much more readable.

  Own Id: OTP-7592 Aux Id: seq11073

### 1.25 Erts 5.6.4.1

#### Improvements and New Features

- A new erts_alloc parameter +M<S>rmbcmt (relative multiblock carrier move threshold) has been added. It determines when to force a moving realloc in a multiblock carrier when a block is shrunk. For more information see the erts_alloc(3) documentation.

  Own Id: OTP-7540

- The new option +d can be given to erl to suppress the crash dump generation if an internal error is detected. As a result, a more useful core dump is produced.

  Own Id: OTP-7578 Aux Id: seq11052

### 1.26 Erts 5.6.4

#### Fixed Bugs and Malfunctions

- Double backslashes in format string passed to the erts internal printf implementation produced erroneous results. No such format strings were passed to the erts internal printf implementation, i.e., the bug was therefore completely harmless. (Thanks to Perry Smith.)

  Own Id: OTP-7408

- Large files are now handled on Windows, where the filesystem supports it.

  Own Id: OTP-7410

- Bug fixed for {packet,http} when space follows http headers.

  Own Id: OTP-7458

- The trace option running could cause an emulator crash if the current function couldn't be determined.

  Own Id: OTP-7484

- Using 16#ffffFFFF as a timeout value in receive...after would often cause a timeout almost at once due to an 32-bit integer overflow. (Thanks to Serge Aleynikov and Matthias Lang.)

  Own Id: OTP-7493

- For the process that an escript runs in, the trap_exit process flag is now false instead of true (as in previous releases). Scripts that depend on the previous (counter-intuitive) behaviour might not work. (Thanks to Bengt Kleberg.)

  *** POTENTIAL INCOMPATIBILITY ***

  Own Id: OTP-7517

- A bug in the string:to_integer/1 builtin made the emulator unstable. This is now corrected. (Thanks to Lev Walkin.)

  Own Id: OTP-7526

#### Improvements and New Features

- Performance for ETS intensive applications should now be better in the SMP emulator. Also, ETS table identifiers (as returned by ets:new/2) are now spread out in wider range than before (using 28 bits in a 32-bit emulator) to make sure that the table identifier for a deleted table will not be quickly re-used.

  NOTE: Table identifiers can now be negative integers. Programs that (incorrectly) assume that table identifiers can only be positive integers might stop to work. (The type of a table identifier is intentionally not documented, and may change in a future release.)

  Own Id: OTP-7348

- New BIF erlang:decode_packet/3 that extracts a protocol packet from a binary. Similar to the socket option {packet, Type}. Also documented the socket packet type http and made it official. NOTE: The tuple format for http packets sent from an active socket has been changed in an incompatible way.

  *** POTENTIAL INCOMPATIBILITY ***

  Own Id: OTP-7404

- The source code for the documentation for some applications (erts, kernel, stdlib, and several others) are now included in the source tar ball. There is currently no Makefile support for building HTML files from the source (such support will be included in a future release).

  Own Id: OTP-7406

- A lot of frequently accessed memory counters (erts internal) have been removed. This since they hurt performance on the runtime system with SMP support. As a result erlang:memory/[0,1] will only deliver a result if all erts_alloc(3) allocators are enabled (default). The result delivered when all erts_alloc(3) allocators are enabled are both more accurate and less accurate than before. More memory than before are included in the result, but the different parts that are summed are not gathered atomically. A call to erlang:memory/[0,1] is much cheaper for the system than before. This since the information isn't gathered atomically anymore which was very expensive.

  *** POTENTIAL INCOMPATIBILITY ***

  Own Id: OTP-7468

- Pre-allocators used for, for example, timers, and messages have been rewritten to be scheduler specific. That is, different schedulers will now allocate from different pools which reduces lock contention.

  Own Id: OTP-7470

- On Mac OS X, file:sync/1 now guarantees that all filesystem buffers are written to the disk by using the fcntl() with F_FULLFSYNC option. Previously, file:sync/1 called fsync(), which only guaranteed that the data had been transferred to the disk drive. (Thanks to Jan Lehnardt.)

  Own Id: OTP-7471

- Termination of a process that takes a long time can now be preempted, i.e., the terminating process will be rescheduled for later continuation of termination so that other processes can execute. Termination of a process that owns many and/or large ets tables typically takes a long time.

  Own Id: OTP-7477

- A new trace option exiting has been added. The exiting trace is similar to the running trace, but for exiting processes. For more information see the erlang(3) documentation.

  The erlang:trace/3 bif now doesn't block other scheduler threads if only one tracee is specified in the call to erlang:trace/3.

  Own Id: OTP-7481

- The re module is extended with repetitive matches (global option) and replacement function.

  Own Id: OTP-7494 Aux Id: OTP-7181

- In the section about binary construction, the reference manual now mentions what happens when an integer value does not fit into an integer segment of size N (namely, that the N least significant bits will be put into into the binary and that the most significant bits will be silently discarded). (Thanks to Edwin Fine.)

  Own Id: OTP-7506

- Setting the {active,once} for a socket (using inets:setopts/2) is now specially optimized (because the {active,once} option is typically used much more frequently than other options).

  Own Id: OTP-7520

#### Known Bugs and Problems

- Floating point arithmetics in drivers can cause a runtime system crash and/or unexpected results on runtime systems with floating point exceptions enabled. Floating point exceptions are disabled unless explicitly enabled or if hipe is enabled.

  Own Id: OTP-7237

### 1.27 Erts 5.6.3.3

#### Fixed Bugs and Malfunctions

- Binary construction with an integer field of size 0 at the end of the constructed binary (and the size given in a variable), would cause a write of one byte outside the memory reserved for the binary, which in turn could cause an emulator crash.

  Own Id: OTP-7422

- A race condition in the dynamic driver implementation could cause an emulator crash. (Thanks to Paul Fisher)

  Own Id: OTP-7464

- Calls to erlang:system_info(allocated_areas) could cause the runtime system with SMP support to crash.

  Own Id: OTP-7474

- The env option to open_port() could cause the runtime system with SMP support to crash.

  Own Id: OTP-7475

#### Improvements and New Features

- Operations that needed to block other threads in the runtime system with SMP support unnecessarily waited for async threads to block. Most important the erlang:memory/[0,1] bif, code loading, and the erlang:trace/3 bif.

  Own Id: OTP-7480

### 1.28 Erts 5.6.3.2

#### Fixed Bugs and Malfunctions

- Calls to erlang:memory/[0,1] could cause the runtime system with SMP support to crash.

  Own Id: OTP-7415

### 1.29 Erts 5.6.3.1

#### Fixed Bugs and Malfunctions

- Doing local call trace on bit syntax matching code that has been optimized with delayed sub-binary creation could crash the emulator.

  Own Id: OTP-7399 Aux Id: seq10978

### 1.30 Erts 5.6.3

#### Fixed Bugs and Malfunctions

- Only one to_erl process at a time is allowed to connect to the same run_erl pipe. Prevents buggy behaviour when IO from several to_erl's get interleaved.

  Own Id: OTP-5107

- IPv6 name resolving has now been fixed to use getaddrinfo() patch (thoroughly reworked) courtesy of Love Hörnquist-Åstrand submitted by Fredrik Thulin. It also can use gethostname2() patch (also reworked) courtesy of Mikael Magnusson for debian submitted by Sergei Golovan.

  Own Id: OTP-5382

- Improved error handling in run_erl

  Own Id: OTP-7252

- A permanent fix for the deadlock issue temporarily fixed by OTP-7260.

  OTP-7260
    The runtime system with SMP support could under rare circumstances deadlock when a distribution channel was taken down while multiple simultaneous operations were performed on it.

  Own Id: OTP-7267 Aux Id: OTP-7260

- ./configure has been improved to find 64-bit OpenSSL libraries.

  Own Id: OTP-7270

- A terminating process could under very rare circumstances trigger a bug which could crash the runtime system with SMP support.

  Own Id: OTP-7272

- SCTP_ADDR_CONFIRMED events are now handled by gen_sctp.

  Own Id: OTP-7276

- binary_to_term/1 would crash the emulator if the binary data contained an external fun with non-atom module and/or function. Corrected to generate a badarg exception.

  Own Id: OTP-7281

- On Mac OS 10.5 (Leopard), sending to socket which the other end closes could cause the emulator to consume 100% CPU time. (Thanks to Matthias Radestock.)

  Own Id: OTP-7289

- The vanilla driver used on Windows could crash the emulator and sometimes produced corrupt files. The vanilla driver is the driver that is used when one only pass a filename as first argument to open_port/2. NOTE: This use of open_port/2 is obsolete, and the documentation of this use has previously been removed. The functionality is only present for backward compatibility reasons and will eventually be removed.

  Own Id: OTP-7301

- Faulty matching in binaries larger than 512Mb on 64bit machines fixed.(On 32bit, the size limit for binaries is still 512Mb). Thanks to Edwin Fine and Per Gustafsson for finding fault and fix.

  Own Id: OTP-7309

- crypto:start() on Windows caused emulator to hang on error popup window if openssl DLL was not found. Windows error popups now suppressed.

  Own Id: OTP-7325

- Configuration option without-termcap can be used to disable the use of termcap libraries for terminal cursor control in the shell.

  Own Id: OTP-7338

- to_erl reports its terminal window size to run_erl in order to get output formatted accordingly

  Own Id: OTP-7342

- On Solaris, the compressed option for file operations did not work if the file descriptor happened to be greater than 255 (a problem with fopen() and friends in Solaris itself).

  Own Id: OTP-7343 Aux Id: seq10949

- A race condition in the runtime system with SMP support causing an erroneous removal of a newly created ets table has been fixed.

  The race occurred when a process removed a table during termination simultaneously as another process removed the same table via ets:delete/1 and a third process created a table that accidentally got the same internal table index as the table being removed.

  Own Id: OTP-7349

- zlib:inflate failed when the size of the inflated data was an exact multiple of the internal buffer size (4000 bytes by default).

  Own Id: OTP-7359

- If the total number of allowed atoms is exceeded, there will now be a controlled termination of the emulator with a crash dump file. The emulator used to simply crash. (Thanks Howard Yeh and Thomas Lindgren.)

  Own Id: OTP-7372

- The break handler in werl on Windows could cause the emulator to hang or crash, that is now corrected.

  Own Id: OTP-7394 Aux Id: seq10969

- The configure script now tests for an serious optimization bug in gcc-4.3.0. If the bug is present, the configure script will abort (if this happens, the only way to build Erlang/OTP is to change to another version of gcc). (Thanks to Mikael Pettersson.)

  Own Id: OTP-7397

#### Improvements and New Features

- On Unix, the emulator now notices when the width of the terminal has changed. (Thanks to Matthew Dempsky and Patrick Mahoney.)

  Own Id: OTP-7290

- There is a new function init:stop/1 which can be used to shutdown the system cleanly AND generate a non-zero exit status or crash dump. (Thanks to Magnus Froberg.)

  Own Id: OTP-7308

- process_info(Pid, garbage_collection) now returns more information

  Own Id: OTP-7311

- The hide option for open_port/2 is now documented. (Thanks to Richard Carlsson.)

  Own Id: OTP-7358

#### Known Bugs and Problems

- Floating point arithmetics in drivers can cause a runtime system crash on runtime systems with floating point exceptions enabled. Floating point exceptions are disabled unless explicitly enabled or if hipe is enabled.

  Own Id: OTP-7237

### 1.31 Erts 5.6.2

#### Fixed Bugs and Malfunctions

- The maximum length of an atom of 255 characters is now strictly enforced. binary_to_term/1 will now fail with a badarg if an encoded term contains an atom longer than 255 characters. Atoms created by drivers will now be truncated to 255 characters if necessary. (Thanks to Matthew Dempsky.)

  Own Id: OTP-7147

- A bug in "bignum handling" on some 64bit architectures could cause rem and div operations on large numbers to hang indefinitely. Rem operations involving the smallest negative number representable in 28 bits or 60 bits could also cause access violation and emulator crash. Both errors are corrected.

  Own Id: OTP-7177

- When doing the initial garbage collection after waking a hibernated process, a fullsweep garbage collection was unnecessarily triggered.

  Own Id: OTP-7212

- The beta testing module gen_sctp now supports active mode as stated in the documentation. Active mode is still rather untested, and there are some issues about what should be the right semantics for gen_sctp:connect/5. In particular: should it be blocking or non-blocking or choosable. There is a high probability it will change semantics in a (near) future patch.

  Try it, give comments and send in bug reports!

  Own Id: OTP-7225

- Invalid arguments to ets:update_counter/3 were not handled correctly. A tuple position (Pos) less than 1 caused the element directly following the key to be updated (as if no position at all had been specified). All invalid values for Pos will now fail with badarg.

  Own Id: OTP-7226

- The runtime system with SMP support could under rare circumstances deadlock when a distribution channel was taken down while multiple simultaneous operations were performed on it.

  Own Id: OTP-7260

#### Improvements and New Features

- More checksum/hash algorithms from the zlib library are now available as built in functions (like md5 hashes has been for a long time).

  Own Id: OTP-7128

- Minor improvements in the garbage collector.

  Own Id: OTP-7139 Aux Id: OTP-7132

- The switch "-detached" to the windows werl program now can create an erlang virtual machine without any main window and without a temporary console showing.

  Own Id: OTP-7142

- erlang:system_info/1 now accepts the logical_processors, and debug_compiled arguments. For more info see the, erlang(3) documentation.

  The scale factor returned by test_server:timetrap_scale_factor/0 is now also effected if the emulator uses a larger amount of scheduler threads than the amount of logical processors on the system.

  Own Id: OTP-7175

- A new BIF ets:update_element/3. To update individual elements within an ets-tuple, without having to read, update and write back the entire tuple.

  Own Id: OTP-7200

- A process executing the processes/0 BIF can now be preempted by other processes during its execution. This in order to disturb the rest of the system as little as possible. The returned result is, of course, still a consistent snapshot of existing processes at a time during the call to processes/0.

  The documentation of the processes/0 BIF and the is_process_alive/1 BIF have been updated in order to clarify the difference between an existing process and a process that is alive.

  Own Id: OTP-7213

### 1.32 Erts 5.6.1.1

#### Fixed Bugs and Malfunctions

- Not enough parameters were passed when sending an error report in erl_check_io.c (Thanks to Matthew Dempsky).

  Own Id: OTP-7176

- In rare circumstances, complex binary matching code could cause the emulator to crash or not match when it should. (Thanks to Rory Byrne.)

  Own Id: OTP-7198

#### Improvements and New Features

- The {allocator_sizes, Alloc} and alloc_util_allocators arguments are now accepted by erlang:system_info/1. For more information see the erlang(3) documentation.

  Own Id: OTP-7167

- The finishing reallocation of the heap block when hibernating a process is now always moving the heap block since it drastically reduces memory fragmentation when hibernating large amounts of processes.

  Own Id: OTP-7187

### 1.33 Erts 5.6.1

#### Fixed Bugs and Malfunctions

- The SMP emulator on sparc64 erroneously used the sparc32 atomic and the sparc32 spinlock implementations which caused it to crash.

  Own Id: OTP-7006

- Call tracing the new guard BIFs byte_size, bit_size, or tuple_size and the loading a module that uses one of those functions, could cause the emulator to terminate.

  Own Id: OTP-7008

- configuring --enable-darwin-universal or --enable-darwin-64bit on MacOSX could result in a non optimized emulator. Top level configure script now corrected.

  Own Id: OTP-7014

- configuring --with-gd did not produce correct include flags for percept.

  Own Id: OTP-7015

- Environment variables weren't handled in thread safe manner in the runtime system with SMP support on Windows.

  erl_drv_putenv(), and erl_drv_getenv() has been introduced for use in drivers. Do not use putenv(), or getenv() directly in drivers. For more information see the erl_driver documentation.

  Own Id: OTP-7035

- HIPE: Corrected the choice of interface to the send/3 and setnode/3 BIFs for native-compiled code. Using the incorrect interface could, in unusual circumstances, lead to random runtime errors.

  Own Id: OTP-7067

- Garbage collections could become extremely slow when there were many keys in the process dictionary. (Thanks to Fredrik Svahn.)

  Own Id: OTP-7068

- The duplicate documentation directory in the windows installation is removed.

  Own Id: OTP-7070

- Documentation bugfixes and clarifications.

  (Thanks to Joern (opendev@gmail.com), Matthias Lang, and Richard Carlsson.)

  Own Id: OTP-7079

- The runtime system with SMP support not using the native atomic integer implementation part of OTP could deadlock when run on a system with more than one logical processor. That is, only the runtime system with SMP support on other hardware platforms than x86, x86_64, sparc32, and powerpc32 were effected by this bug.

  Own Id: OTP-7080

- The break handling code (run when Ctrl-C is hit) could could potentially deadlock the runtime system with SMP support.

  Own Id: OTP-7104

- The sctp driver has been updated to work against newer lksctp packages e.g 1.0.7 that uses the API spelling change adaption -> adaptation. Older lksctp (1.0.6) still work. The erlang API in gen_sctp.erl and inet_sctp.hrl now spells 'adaptation' regardless of the underlying C API.

  *** POTENTIAL INCOMPATIBILITY ***

  Own Id: OTP-7120

- A bug in erlang:phash2/1 on 64-bit platforms has been fixed. (Thanks to Scott Lystig Fritchie.)

  Own Id: OTP-7127

- The emulator could under rare circumstances crash while garbage collecting.

  Own Id: OTP-7132

#### Improvements and New Features

- The documentation has been updated so as to reflect the last updates of the Erlang shell as well as the minor modifications of the control sequence p of the io_lib module.

  Superfluous empty lines have been removed from code examples and from Erlang shell examples.

  Own Id: OTP-6944 Aux Id: OTP-6554, OTP-6911

- Bit syntax construction with a small integer in a non-byte aligned field wider than the CPU's word size could cause garbage bits in the beginning of the field.

  Own Id: OTP-7085

- All Windows versions older than Windows 2000 are now not supported by the Erlang runtime system. This since there was a need for usage of features introduced in Windows 2000.

  Own Id: OTP-7086

- Memory management improvements especially for the runtime system with SMP support:

  - The runtime system with SMP support can now use multiple, thread specific instances of most memory allocators. This improves performance since it reduces lock contention in the memory allocators. It may however increase memory usage for some applications. The runtime system with SMP support will by default enable this feature on most allocators. The amount of instances used can be configured.
  - driver_alloc(), driver_realloc(), and driver_free() now use their own erts specific memory allocator instead of the default malloc() implementation on the system.
  - The default configuration of some allocators have been changed to fit applications that use much memory better.
  - Some new erts_alloc configuration parameters have been added.
  - erts_alloc_config has been modified to be able to create configurations suitable for multiple instances of allocators.
  - The returned value from erlang:system_info({allocator, Alloc}) has been changed. This since an allocator may now run in multiple instances.

  If you for some reason want the memory allocators to be configured as before, you can pass the +Mea r11b command-line argument to erl.

  For more information see the erts_alloc(3), the erts_alloc_config(3), and the erlang(3) documentation.

  *** POTENTIAL INCOMPATIBILITY ***

  Own Id: OTP-7100

- On Unix, denormalized floating point numbers could not be created using list_to_float/1 or binary_to_term/1. (Thanks to Matthew Dempsky.)

  Own Id: OTP-7122

- Native atomic integers and spin-locks are now also available for the runtime system with SMP support on sparc64.

  Own Id: OTP-7130

- FP exceptions support for sparc64 userspace on Linux has been added. Note that FP exception support is now turned off by default, so to actually enable it you need to do './configure --enable-fp-exceptions'.

  Own Id: OTP-7131

### 1.34 Erts 5.6

#### Fixed Bugs and Malfunctions

- A bug for raw files when reading 0 bytes returning 'eof' instead of empty data has been corrected.

  Own Id: OTP-6291 Aux Id: OTP-6967

- All exported functions in gzio.c have now been renamed to avoid conflict with drivers that are indirectly linked with an external zlib library.

  Own Id: OTP-6816 Aux Id: OTP-6591

- On the 64-bit Erlang emulator, bit syntax construction with integers containing more than 60 bits ("big numbers") into fields with more than 60 bits could produce incorrect results.

  Own Id: OTP-6833

- When the runtime system failed to allocate memory for binaries, it could dead lock while writing the erl_crash.dump.

  Own Id: OTP-6848

- The runtime system with SMP support could deadlock if a process called the erlang:suspend_process(Pid) BIF or the erlang:garbage_collect(Pid) BIF while the process identified by Pid was currently running and the process calling the BIFs was terminated during the call to the BIFs.

  Processes suspending each other via the erlang:suspend_process/1 BIF or garbage collecting each other via the erlang:garbage_collect/1 BIF could deadlock each other when the runtime system with SMP support was used.

  Own Id: OTP-6920

- dbg could leave traced processes in a suspended state if the tracer process was killed with exit reason kill.

  erlang:suspend_process/2 has been introduced which accepts an option list as second argument. For more information see the erlang(3) documentation.

  Processes suspended via erlang:suspend_process/[1,2] will now be automatically resumed if the process that called erlang:suspend_process/[1,2] terminates.

  Processes could previously be suspended by one process and resumed by another unless someone was tracing the suspendee. This is not possible anymore. The process resuming a process has to be the one that suspended it.

  *** POTENTIAL INCOMPATIBILITY ***

  Own Id: OTP-6946

- file:write_file/3, file:write/2 and file:read/2 could crash (contrary to documentation) for odd enough file system problems, e.g write to full file system. This bug has now been corrected.

  In this process the file module has been rewritten to produce better error codes. Posix error codes now originate from the OS file system calls or are generated only for very similar causes (for example 'enomem' is generated if a memory allocation fails, and 'einval' is generated if the file handle in Erlang is a file handle but currently invalid).

  More Erlang-ish error codes are now generated. For example {error,badarg} is now returned from file:close/1 if the argument is not of a file handle type. See file(3).

  The possibility to write a single byte using file:write/2 instead of a list or binary of one byte, contradictory to the documentation, has been removed.

  *** POTENTIAL INCOMPATIBILITY ***

  Own Id: OTP-6967 Aux Id: OTP-6597 OTP-6291

- Monitor messages produced by the system monitor functionality, and garbage collect trace messages could contain erroneous heap and/or stack sizes when the actual heaps and/or stacks were huge.

  As of erts version 5.6 the large_heap option to erlang:system_monitor/[1,2] has been modified. The monitor message is sent if the sum of the sizes of all memory blocks allocated for all heap generations is equal to or larger than the specified size. Previously the monitor message was sent if the memory block allocated for the youngest generation was equal to or larger than the specified size.

  *** POTENTIAL INCOMPATIBILITY ***

  Own Id: OTP-6974 Aux Id: seq10796

- inet:getopts/2 returned random values on Windows Vista.

  Own Id: OTP-7003

#### Improvements and New Features

- The emulator internal process lock implementation has been rewritten and optimized. A slight risk of starvation existed in the previous implementation. This risk has also been eliminated in the new implementation.

  Own Id: OTP-6500

- Bitstrings (bit-level) binaries and binary comprehensions are now part of the language. See the Reference Manual.

  Own Id: OTP-6558

- The windows version of erlang now has SMP support. The SMP emulator is run by default on machines which shows more than one virtual or physical processor.

  Own Id: OTP-6560 Aux Id: OTP-6925

- The details of the compressed term format has been documented in erl_ext_dist.txt. (Thanks to Daniel Goertzen.)

  Own Id: OTP-6755

- The runtime system with SMP support is now started by default if more than one logical processor are detected. For more information, see the erl(3) documentation.

  Own Id: OTP-6756

- The external format for Erlang terms and the distribution protocol are now documented in ERTS User's Guide.

  Own Id: OTP-6779

- New BIF's erlang:system_profile/1 and erlang:system_profile/2. These BIF's controls concurrency profiling options for processes, ports and schedulers.

  Own Id: OTP-6783 Aux Id: OTP-6285

- The ErlDrvTermData term types used by driver_output_term() and driver_send_term() have been extended with the term types ERL_DRV_BUF2BINARY, ERL_DRV_EXT2TERM, and ERL_DRV_UINT. ERL_DRV_BUF2BINARY is used for passing and creating a binary, ERL_DRV_EXT2TERM is used for passing terms encoded with the external term format, and ERL_DRV_UINT is used for passing unsigned integers.

  Also the data types ErlDrvUInt and ErlDrvSInt have been added which makes it more obvious how arguments to term types are interpreted with regards to width and signedness.

  The incorrect data types ErlDriverTerm, ErlDriverBinary, and ErlDriverPort in the erl_driver(3) documentation have been replaced with the correct data types ErlDrvTermData, ErlDrvBinary, and ErlDrvPort.

  For more information see the erl_driver(3) documentation.

  Own Id: OTP-6823

- Miscellaneous improvements of the erts internal thread library.

  It now support optimized atomic operations and spin-locks on windows.

  Fall-backs based on mutexes and/or spin-locks for missing optimized atomic operations, spin-locks, or rwlocks has been implemented. This makes it possible to compile the runtime system with SMP support on a lot more platforms.

  Default stack size on OpenBSD has been increased to 256 kilo-words.

  Own Id: OTP-6831 Aux Id: OTP-6560

- Many bit syntax operations, both construction and matching, are faster. For further information, see the Efficiency Guide.

  Own Id: OTP-6838

- Literal lists, tuples, and binaries are no longer constructed at run-time as they used to be, but are stored in a per-module constant pool. Literals that are used more than once are stored only once.

  This is not a change to the language, only in the details of its implementation. Therefore, the implications of this change is described in the Efficiency Guide.

  Example 1: In the expression element(BitNum-1, {1,2,4,8,16,32,64,128}), the tuple used to be constructed every time the expression was executed, which could be detrimental to performance in two ways if the expression was executed in a loop: the time to build the tuple itself and the time spent in garbage collections because the heap filled up with garbage faster.

  Example 2: Literal strings, such as "abc", used to be stored in the compiled code compactly as a byte string and expanded to a list at run-time. Now all strings will be stored expanded to lists (such as [$a,$b,$c]) in the constant pool. That means that the string will be faster to use at run-time, but that it will require more space even when not used. If space is an issue, you might want to use binary literals (that is, <<"abc">>) instead of string literals for infrequently used long strings (such as error messages).

  Own Id: OTP-6850

- The Erlang driver API has been extended with a portable POSIX thread like API for multi-threading. The Erlang driver thread API provides:

  - Threads
  - Mutexes
  - Condition variables
  - Read/Write locks
  - Thread specific data

  For more information see the erl_driver(3) documentation.

  Own Id: OTP-6857

- Recursive calls now usually consume less stack than in R11B. See the Efficiency Guide.

  Own Id: OTP-6862 Aux Id: seq10746

- The deprecated BIFs erlang:old_binary_to_term/1 and erlang:info/1 have been removed.

  *** POTENTIAL INCOMPATIBILITY ***

  Own Id: OTP-6876

- Calls to driver call-backs triggered by external events are now scheduled and interleaved with execution of Erlang processes also on the runtime system without SMP support.

  Own Id: OTP-6878

- Faster arithmetic of integers of more than 27 bits signed (or 60 bits signed on an 64-bit CPU), and also faster integer multiplication. (Thanks to Tony Rogvall.)

  Own Id: OTP-6891

- Significant improvements of the process_info BIFs:

  - process_info/2 can now be called with a list of items as second argument in order to atomically retrieve information about multiple items.
  - process_info/[1,2] has been optimized in the runtime system with SMP support. The whole scheduler could previously be blocked for a significant period of time in process_info/[1,2] waiting for a lock on the process being inspected. The Erlang process calling process_info/[1,2] can still be blocked for a significant period of time waiting for the lock, but the scheduler will now be able to run other processes while the process calling process_info/[1,2] waits for the lock.
  - process_info/2 now accept a few more items than before.
  - The documentation of process_info/[1,2] has been improved.

  For more information see the erlang(3) documentation.

  Own Id: OTP-6899

- open_port({}, []) could crash the emulator. (Thanks to Matthew Dempsky.)

  Own Id: OTP-6901

- Two new guard BIFs have been introduced as a recommended replacement for size/1. (The size/1 BIF will be removed no earlier than in R14B.) The BIFs are tuple_size/1 to calculate the size of a tuple and byte_size/1 to calculate the number of bytes needed for the contents of the binary or bitstring (rounded up to the nearest number of bytes if necessary).

  There is also a new bit_size/1 BIF that returns the exact number of bits that a binary or bitstring contains.

  Own Id: OTP-6902

- The ets:fixtable/2 function, which has been deprecated for several releases, has been removed.

  The ets:info/1 function has been reimplemented as a BIF, which guarantees that information returned is consistent.

  The ets:info/2 function now fails with reason badarg if the second argument is invalid. (Dialyzer can be used to find buggy code where the second argument is misspelled.)

  *** POTENTIAL INCOMPATIBILITY ***

  Own Id: OTP-6906

- As the linux kernel may generate a minor fault when tracing with CPU timestamps, and there exists no patch to the Linux kernel that fixes the problem, cpu timestamps are disabled on Linux for now.

  *** POTENTIAL INCOMPATIBILITY ***

  Own Id: OTP-6922

- The functions io:columns/0, io:columns/1, io:rows/0 and io:rows/1 are added to allow the user to get information about the terminal geometry. The shell takes some advantage of this when formatting output. For regular files and other io-devices where height and width are not applicable, the functions return {error,enotsup}.

  Potential incompatibility: If one has written a custom io-handler, the handler has to either return an error or take care of io-requests regarding terminal height and width. Usually that is no problem as io-handlers, as a rule of thumb, should give an error reply when receiving unknown io-requests, instead of crashing.

  *** POTENTIAL INCOMPATIBILITY ***

  Own Id: OTP-6933

- driver_caller() can now also be used from the start callback of a driver.

  Own Id: OTP-6951

- The emulator can now be compiled for 64bit intel, as well as a 32bit universal binary on darwin/MacOSX 10.4 and 10.5.

  Own Id: OTP-6961

- If open_port fails because all available ports are already in use, it will now throw a system_limit exception instead of an enfile exception. (enfile might still be thrown if the operating system would return ENFILE.)

  Own Id: OTP-6968

- The spawn_monitor/1 and spawn_monitor/3 BIFs are now auto-imported (i.e. they no longer need an erlang: prefix).

  Own Id: OTP-6975

- On Windows, the werl window now handles resize, so that the whole window can be utilized. Text selection is also updated to be line oriented instead of rectangle oriented as in earlier versions.

  Own Id: OTP-6994 Aux Id: OTP-6933

- Kqueue support (kernel-poll) has been enabled on FreeBSD. The problem with kqueue not detecting writes on a pipe on FreeBSD was actually not a kqueue issue, but a writev on pipes issue. Neither poll(), nor select() detected the write when the bug hit. NetBSD and DragonFlyBSD probably have or have had the same bug. This bug should have been fixed in FreeBSD 6.3 and FreeBSD 7.0 thanks to Jean-Sebastien Pedron.

  Own Id: OTP-7001

### 1.35 Erts 5.5.5.5

#### Fixed Bugs and Malfunctions

- Hanging writes on temporarily unavailable NFS filesystems could cause the execution of (not file related) erlang code to get blocked even though I/O threads were used. This is now corrected.

  Own Id: OTP-6907 Aux Id: seq10771

### 1.36 Erts 5.5.5.4

#### Fixed Bugs and Malfunctions

- Data passed to a driver via erlang:port_call could be corrupted when the runtime system with SMP support was used. (Thanks to YAMASHINA Hio.)

  Own Id: OTP-6879

- In the SMP emulator, if several processes called ets:update_counter/3 (even for different tables) when the counter values exceeded 27 bits, the counter values could be corrupted or the emulator could crash.

  Own Id: OTP-6880 Aux Id: seq10760

### 1.37 Erts 5.5.5.3

#### Fixed Bugs and Malfunctions

- Creating a named table using ets:new/2 or renaming a named table using ets:rename/2 could in rare circumstances succeed, meaning that there would be two or more tables with the same name. Now such call will fail with a badarg exception as it is supposed to do.

  ets:delete/1 used on a named table now removes the name immediately so that a new table with the same name can be created.

  Turning on call trace on the internal BIF that implements ets:delete/1 would crash the emulator.

  SMP emulator only: Using ets:rename/2 on a table that ets:safe_fixtable/2 has been used on could cause an emulator crash or undefined behaviour because of a missing lock.

  Own Id: OTP-6872 Aux Id: seq10756, seq10757

### 1.38 Erts 5.5.5.2

#### Known Bugs and Problems

- ets:select/3 on ordered_set and with a chunksize a multiple of 1000 gave all elements instead of just 1000. Also ets:slot/2 on ordered set could give unexpected results on SMP emulator. Both problems are corrected.

  Own Id: OTP-6842

### 1.39 Erts 5.5.5.1

#### Fixed Bugs and Malfunctions

- All exported functions in gzio.c have now been renamed to avoid conflict with drivers that are indirectly linked with an external zlib library.

  Own Id: OTP-6816 Aux Id: OTP-6591

- Calling binary_to_term/1 with certain invalid binaries would crash the emulator.

  Own Id: OTP-6817

#### Improvements and New Features

- Restored speed of bit-syntax matching of 32 bits integers.

  Own Id: OTP-6789 Aux Id: seq10688

### 1.40 Erts 5.5.5

#### Fixed Bugs and Malfunctions

- The functions in gzio.c have been renamed to avoid conflict with drivers that indirectly linked with an external zlib library.

  Own Id: OTP-6591

- The emulator without SMP support dumped core if an async-thread finished a job after the emulator had begun writing an erl_crash.dump.

  Own Id: OTP-6685

- In bit syntax matching, integer fields with greater size than 16Mb would fail to match. (Thanks to Bertil Karlsson and Francesco Pierfederici.)

  Matching out a 32-bit integer not aligned on a byte boundary from a binary could cause an heap overflow (and subsequent termination of the emulator).

  A module that contained bit syntax construction with a literal field size greater than 16Mb would fail to load.

  Several other similar bugs having to do with huge field sizes were eliminated.

  Attempting to construct a binary longer than 536870911 bytes will now fail with a system_limit exception (rather than fail in mysterious ways or construct an binary with incorrect contents). Similarily, attempting to match a binary longer than 536870911 bytes will now fail (instead of producing an incorrect result). This limitation has been documented in the Efficiency Guide. (The limit is in the 32-bit emulator; use the 64-bit emulator if you need to handle larger binaries than 536870911.)

  Own Id: OTP-6686

- Bugs in rem and div of very large numbers are corrected.

  Own Id: OTP-6692

- erlang:system_info({allocator, Alloc}) didn't allocate enough heap when a bignum was part of the result which could cause an emulator crash.

  Own Id: OTP-6693

- It was previously not possible to pass erts_alloc the same configuration via the command-line, as used by default.

  A +M* command-line argument that configure a size of some sort can now be passed a value that equals the size of the address space. The value used, in this case, will be "the size of the address space" - 1.

  Own Id: OTP-6699

- SysIOVec* driver_peekq(ErlDrvPort port, int *vlen) did not update *vlen if port was invalid. *vlen is now set to -1 if the port is invalid.

  The efile driver expects *vlen to be updated also when the port is invalid. This situation occurs seldom, but when the runtime system has async-threads enabled and ports are killed it can. When it occurred the runtime system crashed.

  Own Id: OTP-6729

#### Improvements and New Features

- For scripts written using escript, there is a new function escript:script_name/0, which can be used to retrieve the pathame of the script. The documentation has been clarified regarding pre-defined macros such as ?MODULE and the module name.

  Own Id: OTP-6593

- The section Guards in the chapter The Abstract Format of the ERTS User's Guide has been updated.

  Own Id: OTP-6600

- Corrected protocol layer flue for socket options SO_LINGER, SO_SNDBUF and SO_RCVBUF, for SCTP.

  Own Id: OTP-6625 Aux Id: OTP-6336

- The behaviour of the inet option {active,once} on peer close is improved and documented.

  Own Id: OTP-6681

- The inet option send_timeout for connection oriented sockets is added to allow for timeouts in communicating send requests to the underlying TCP stack.

  Own Id: OTP-6684 Aux Id: seq10637 OTP-6681

- The command line flag -args_file FileName, and the environment variables ERL_AFLAGS, and ERL_ZFLAGS for the erl command have been added. For more information see the erl(1) documentation.

  Own Id: OTP-6697

- The is_constant/1 type test has been deprecated. is_constant/1 is improperly named and almost entirely undocumented.

  Own Id: OTP-6731

### 1.41 Erts 5.5.4.3

#### Fixed Bugs and Malfunctions

- process_flag(trap_exit, Bad) where Bad was a term not equal to true or false, didn't fail with badarg as it should; instead, the failure was silently ignored. This bug was introduced in erts-5.5.2.

  Own Id: OTP-6627 Aux Id: OTP-6160

- The minimum and default stack size for async-threads has been increased to 16 kilowords. This since the previous minimum and default stack size of 8 kilowords proved to be too small (introduced in erts-5.5.4.2).

  Own Id: OTP-6628 Aux Id: OTP-6580, Seq10633

#### Improvements and New Features

- process_flag/2 accepts the new flag sensitive.

  Own Id: OTP-6592 Aux Id: seq10555

### 1.42 Erts 5.5.4.2

#### Fixed Bugs and Malfunctions

- When a port steals control over a file descriptor from another port, the stealing port tests if the other port is alive. This in order to be able to give an accurate error message. In the runtime system with SMP support, this test was done without appropriate locks held. This could in worst case lead to an erroneous error message; therefore, this bug is to be considered harmless.

  Own Id: OTP-6602

#### Improvements and New Features

- The default stack size for threads in the async-thread pool has been shrunk to 8 kilowords, i.e., 32 KB on 32-bit architectures. This small default size has been chosen since the amount of async-threads might be quite large. The default stack size is enough for drivers delivered with Erlang/OTP, but might not be sufficiently large for other dynamically linked in drivers that use the driver_async() functionality. A suggested stack size for threads in the async-thread pool can be configured via the +a command line argument of erl(1).

  *** POTENTIAL INCOMPATIBILITY ***

  Own Id: OTP-6580

### 1.43 Erts 5.5.4.1

#### Fixed Bugs and Malfunctions

- Setting the time on the system while using heart on a linux machine where the emulator was built with clock_gettime support (default from Linux 2.6/erts-5.5.4 and upwards), could make the heart command fire. This was due to bug in the heart executable which is now corrected.

  Own Id: OTP-6598 Aux Id: seq10614

### 1.44 Erts 5.5.4

#### Fixed Bugs and Malfunctions

- Corrected misspelling of '-pz' in the help text for erlc. (Thanks to Ulf Wiger.)

  Own Id: OTP-6433

- The MD5 calculation of a BEAM file done by code:module_md5/1, beam_lib:md5/1, and by the compiler for the default value of the vsn attribute have all been changed so that its result will be the same on all platforms; modules containing funs could get different MD5s on different platforms.

  Own Id: OTP-6459

- The emulator could dump core while writing an erl_crash.dump file if there were funs with a large terms in its environment. Since there is no way to inspect a fun's environment in the crashdump_viewer application anyway, a variables in the environment are now set to [] before dumping the fun. (Thanks to Jean-Sebastien Pedron.)

  Own Id: OTP-6504

- {Port, {exit_status, S}} messages from ports opened with the exit_status option could under rare circumstances be delayed. This bug was present on Erlang runtime systems without SMP support on all unix operating systems other than SunOS.

  Own Id: OTP-6528

- A bug in linuxthreads could cause the emulator to dump core when dlerror() was called before the first call to dlopen(). As a workaround the emulator always makes a call to dlopen() on initialization when linuxthreads is used as thread library.

  Own Id: OTP-6530

- file:sync/1 did not do anything on Windows. Now it calls the system function for flushing buffers (FlushFileBuffers()). (Thanks to Matthew Sackman.)

  Own Id: OTP-6531

- open_port/2 could on the runtime system with SMP support fail with the wrong exit reason when a port couldn't be created. When this happened the exit reason was typically eintr, or ebusy instead of eagain.

  Own Id: OTP-6536

- The file driver (efile_drv) did not flush data written using the option 'delayed_write' after the set timeout time, rather at the next file operation. This bug has now been corrected.

  Own Id: OTP-6538

#### Improvements and New Features

- An interface towards the SCTP Socket API Extensions has been implemented.It is an Open Source patch courtesy of Serge Aleynikov and Leonid Timochouk. The Erlang code parts has been adapted by the OTP team, changing the Erlang API somewhat.

  The Erlang interface consists of the module gen_sctp and an include file -include_lib("kernel/include/inet_sctp.hrl"). for option record definitions. The gen_sctp module is documented.

  The delivered Open Source patch, before the OTP team rewrites, was written according to http://tools.ietf.org/html/draft-ietf-tsvwg-sctpsocket-13 and was claimed to work fine, tested on Linux Fedora Core 5.0 (kernel 2.6.15-2054 or later) and on Solaris 10 and 11. The OTP team rewrites used the same standard document but might have accidentally broken some functionality. If so it will soon be patched to working state. The tricky parts in C and the general design has essentially not changed. During the rewrites the code was hand tested on SuSE Linux Enterprise Server 10, and briefly on Solaris 10. Feedbach on code and docs is very much appreciated.

  The SCTP interface is in beta state. It has only been hand tested and has no automatic test suites in OPT meaning everything is most certainly not tested. Socket active mode is broken. IPv6 is not tested. The documentation has been reworked due to the API changes, but has not been proofread after this.

  Thank you from the OTP team to Serge Aleynikov and Leonid Timochouk for a valuable contribution. We hope we have not messed it up too much.

  Own Id: OTP-6336

- A {minor_version,Version} option is now recognized by term_to_binary/2. {minor_version,1} will cause floats to be encoded in an exact and more space-efficient way compared to the previous encoding.

  Own Id: OTP-6434

- There is a new escript program that can be used for writing scripts in Erlang. Erlang scripts don't need to be compiled and any arguments can be passed to them without risk that they are interpreted by the Erlang system.

  Own Id: OTP-6505

- Setting and getting socket options in a "raw" fashion is now allowed. Using this feature will inevitably produce non portable code, but will allow setting ang getting arbitrary uncommon options on TCP stacks that do have them.

  Own Id: OTP-6519

- Miscellaneous signal handling improvements on the Erlang runtime system with SMP support.

  The fallback implementation of spin locks and atomic operations are now implemented using pthread spin locks when pthread spin locks are found on the system.

  The Erlang runtime system with SMP support can now run on Linux systems that has Linuxthreads instead of NPTL (Native POSIX Thread Library). Note that the SMP support hasn't been as thoroughly tested with Linuxthreads as with NPTL. A runtime system with SMP support will therefore not be built by default on Linux when NPTL isn't found. In order to force a build of the runtime system with SMP support, pass --enable-smp-support to configure when building OTP.

  Own Id: OTP-6525

### 1.45 Erts 5.5.3.1

#### Fixed Bugs and Malfunctions

- erlang:system_flag(multi_scheduling, block) could cause the emulator with SMP support to deadlock.

  Own Id: OTP-6431 Aux Id: OTP-6403

- The runtime system with SMP support failed to call the driver timeout callback of ports in state closing. This could cause ports to fail flushing their I/O queues.

  Own Id: OTP-6432

- The {Port, closed} message from a closed port could arrive at the port owner before Port had been removed from the result of erlang:ports/0 in the runtime system with SMP support.

  Own Id: OTP-6437

- The async id of async jobs created via driver_async wasn't created in a thread safe manner in the runtime system with SMP support. This could in worst case cause driver_async_cancel() to cancel another async job than intended.

  Own Id: OTP-6438

- Under rare circumstances a terminating connection between two nodes could cause an instantaneous reconnect between the two nodes to fail on the runtime system with SMP support.

  Own Id: OTP-6447

- In the documentation of the driver entry field extended_marker of erts version 5.5.3 (driver_entry(3)), the following is stated: "The following fields are ignored if this field is equal to 0". This is a documentation bug and has been changed to: "If this field is equal to 0, all the fields following this field also have to be 0, or NULL in case it is a pointer field".

  The runtime check for detection of old incompatible drivers made when loading drivers has been improved. The emulator can, however, not make sure that a driver that doesn't use the extended driver interface isn't incompatible. Therefore, when loading a driver that doesn't use the extended driver interface, there is a risk that it will be loaded also when the driver is incompatible. When the driver use the extended driver interface, the emulator can verify that it isn't of an incompatible driver version. You are therefore advised to use the extended driver interface.

  For more information see the erl_driver(3) and driver_entry(3) documentation.

  Own Id: OTP-6452 Aux Id: OTP-6330

- When terminating ports on the runtime system with SMP support, removal of links to processes was done without locking the link lock on processes. This could cause an emulator crash.

  Own Id: OTP-6475

- The emulator with SMP support could crash when a port flushed its I/O queue by calling driver_async() from the timeout driver callback.

  Own Id: OTP-6479

- Large exit reasons could under rare circumstances cause the runtime system with SMP support to crash.

  Own Id: OTP-6521

#### Improvements and New Features

- Faster system calls for keeping the time accurate are used on newer Linux kernels, which can result in a significant speed-up of the emulator on those systems.

  Own Id: OTP-6430

- Added number of async threads and number of scheduler threads to the system information that can be retrieved via driver_system_info(). For more information see the erl_driver(3) documentation.

  Own Id: OTP-6440

- When SIGUSR1 is received by the runtime system with SMP support, the erl_crash.dump is now written by a special thread, instead of as before directly from the signal handler.

  Own Id: OTP-6465

- term_to_binary/2 with compression is now faster.

  term_to_binary/2 now accepts the option '{compressed,Level}' for specifying the compression level. Level must be in the range 0 (no compression) through 9 (highest compression level). Default is 6.

  Future compatibility bugfix: binary_to_term/1 did not handle the Uniq and Index fields correctly.

  Own Id: OTP-6494

- Removed unnecessary reallocation when initializing kernel-poll set.

  Own Id: OTP-6516

### 1.46 Erts 5.5.3

#### Fixed Bugs and Malfunctions

- Node and fun table entries could under rare circumstances be deallocated multiple times on the emulator with SMP support.

  Own Id: OTP-6369

- epoll_wait() can repeat entries for the same file descriptor in the result array. This could cause the ready_input, ready_output, or event callbacks of a driver to unintentionally be called multiple times. We have only noted repeated entries when an error condition has occurred on the file descriptor. In this case, the repeated entries should normally not be a problem for the driver since it should detect the error and de-select the file descriptor. Therefore this bug should be considered harmless. The emulator now coalesce repeated entries into one.

  You are only affected by this bug if you are using erts-5.5.2.* and the kernel-poll feature on linux.

  Own Id: OTP-6376 Aux Id: OTP-6222

- If a process that was waiting in gen_tcp:accept/1 was killed, calling gen_tcp:accept/1 again on the same listen socket would fail with '{error,einval}'.

  Own Id: OTP-6381 Aux Id: seq10535

- The emulator failed to start on Solaris 10 when kernel-poll support was enabled and the maximum number of filedescriptors configured was less than or equal to 256.

  Own Id: OTP-6384 Aux Id: OTP-6222

- The R10B compiler could generate unsafe bs_save/bs_restore instructions that could cause memory corruption. (The R11B compiler does not have that problem.) The erlang emulator will now refuse to load R10B-compiled modules that contain such unsafe bs_save/bs_restore instructions. In addition, the beam_validator module in the compiler will also reject such instructions (in case it is used to validate R10B code). (Thanks to Matthew Reilly.)

  Own Id: OTP-6386

- Process and port timers could fail to work properly on the runtime system with SMP support. Many thanks to Dmitriy Kargapolov and Serge Aleynikov who tracked down this bug.

  Own Id: OTP-6387

- Bit syntax code compiled by an R10B compiler that matched out a floating point number would not properly check that the floating point number was valid; if the float was, for instance, NaN the emulator could crash.

  Own Id: OTP-6395

- statistics(runtime) on Windows used to return the elapsed system time for the process, instead of the user time. Corrected. (Thanks to Robert Virding.)

  Own Id: OTP-6407

- A loadable driver (loaded by erl_ddll) which used driver_async() would cause the emulator to crash. (Thanks to Dmitriy Kargapolov.)

  Own Id: OTP-6410

- Under rare circumstances the emulator on unix platforms could fail to terminate the Erlang port corresponding to a port program opened with the exit_status option.

  Own Id: OTP-6411

- A link removed via unlink/1 could under rare circumstances transfer exit signals for a short period of time after the call to unlink/1 had returned when the runtime system with SMP support was used.

  Own Id: OTP-6425 Aux Id: OTP-6160

#### Improvements and New Features

- In the runtime system with SMP support, ports are now being scheduled on the scheduler threads interleaved with processes instead of being run in a separate I/O thread.

  Own Id: OTP-6262

- More interfaces are added in erl_ddll, to support different usage scenarios.

  Own Id: OTP-6307 Aux Id: OTP-6234

- In the runtime system with SMP support, the global I/O lock has been replaced with a more fine grained port locking scheme. Port locking is either done on driver level, i.e., all ports executing the same driver share a lock, or on port level, i.e., each port has its own lock. Currently the inet driver, the efile driver, and the spawn driver use port level locking and all other statically linked in drivers use driver level locking. By default dynamically linked in drivers will use locking on driver level. For more information on how to enable port level locking see the erl_driver(3) and the driver_entry(3) man pages.

  As of erts version 5.5.3 the driver interface has been extended. The extended interface introduce version management, the possibility to pass capability flags to the runtime system at driver initialization, and some new driver API functions. For example, the driver_system_info() function which can be used to determine if the driver is run in a runtime system with SMP support or not. The extended interface doesn't have to be used, but dynamically linked in driver have to be recompiled. For information see the erl_driver(3) and the driver_entry(3) man pages.

  NOTE: Dynamically linked in drivers have to be recompiled.

  *** POTENTIAL INCOMPATIBILITY ***

  Own Id: OTP-6330 Aux Id: OTP-6262

- A test and debug feature which modifies the timing of the runtime system has been added. For more information, see documentation of the +T<Level> command line argument of erl(1).

  Own Id: OTP-6382

- The version of zlib (http://zlib.net) linked into run-time system has been updated to version 1.2.3.

  Own Id: OTP-6394

- The erlc program now passes on the -smp and -hybrid options to the Erlang emulator it starts. This is mainly useful for compiling native code, because native code must be compiled with same type of run-time system as in which it will be run.

  If the -s option is given, erlc now prints a warning that it is deprecated and that it will be removed in R12B.

  Own Id: OTP-6398

- The schedulers option of erlang:system_flag/2 has been removed, i.e., the number of scheduler threads cannot be changed after emulator boot time any more.

  A multi_scheduling option has been added to erlang:system_flag/2. This option can be used for blocking and unblocking multi-scheduling. For more information see the erlang(3) documentation.

  Own Id: OTP-6403

- A port program that had been started with the exit_status option and closed one of the pipes used for communication with the emulator caused the emulator to continuously poll for termination of the port program. This only became a problem when the emulator didn't have other things to do and the port program closed a pipe much earlier than it terminated. When the emulator had other things to do, such as running Erlang processes, the emulator polled for termination in between scheduling of processes.

  Now the emulator doesn't poll for termination of the port program at all; instead, it waits for the child signal from the terminated port program to arrive and then schedules the Erlang port for termination.

  The termination of any port programs have also been optimized. Previously the termination of any port program did always cause a scan of a table of the size equal to maximum number of file descriptors. If the maximum number of file descriptors was large, this scan could be quite expensive. Now the search have been reduced to the set of ports started with the exit_status option.

  Note, all of the above only applies to Erlang emulators on Unix platforms.

  Own Id: OTP-6412 Aux Id: seq10194

- * BEAM: added support for floating-point exceptions on FreeBSD (32-bit x86)

  * SMP: made locking procedures work even when native lock operations aren't implemented

  * SMP: improved timing accuracy in the timer thread (if enabled)

  Own Id: OTP-6424

### 1.47 Erts 5.5.2.2

#### Fixed Bugs and Malfunctions

- A bug in the kernel poll implementation could cause the emulator to omit polling for events on file descriptors. The bug was only present when using the kernel poll implementation based on epoll or kqueue. This bug was introduced in erts-5.5.2.

  Own Id: OTP-6344 Aux Id: OTP-6222

### 1.48 Erts 5.5.2.1

#### Fixed Bugs and Malfunctions

- The run_erl program now acquires its pseudo-ttys using openpty(3), so that it will work on newer Linux distributions that don't have the traditional pseudo-tty devices in the file system. On platforms that don't have openpty(3), run_erl will still search for pseudo-tty devices in the file system.

  The run_erl program will now wait using waitpid(3) to prevent the program it spawned to become defunct. run_erl will also terminate after a delay of 5 seconds (to allow any pending output to be written to the log file) if the spawned program terminates even if some child of it still holds stdin and/or stdout open.

  Own Id: OTP-6225 Aux Id: seq10500

- A bug in ordered_set ETS datatyp caused ets:select (and match) to return faulty results when the table contained process id's from another node.

  Own Id: OTP-6338

### 1.49 Erts 5.5.2

#### Fixed Bugs and Malfunctions

- erlc: A typo in the help text for '-pa path' was corrected.

  Own Id: OTP-6218

- Failure in port command/control driver callbacks could crash the non-SMP emulator. This bug was introduced in the 5.5 version of erts.

  Own Id: OTP-6224

- Erroneous "Input driver gone away without deselecting!" error reports could sometimes occur when a driver instance terminated in the ready_output() callback of the driver. This bug was only present in emulators that used poll(). Note, that this bug was harmless, the only effect it had was the erroneous error report.

  Own Id: OTP-6229 Aux Id: OTP-3993, Seq5266, Seq7247, OTP-4307

- The emulator could cause a type assertion failure while writing an erl_crash.dump, causing the erl_crash.dump to be terminated and a core dump generated.

  Own Id: OTP-6235 Aux Id: seq10444

- The registered name of a process is now the last observable resource removed before links and monitors are triggered when a process terminates.

  Previously ets tables were removed after the registered name. This could cause problems on the runtime system with SMP support for code that expected that ets tables owned by a specific process had been removed if the name of the process had been removed.

  Own Id: OTP-6237

- Failure to fork() a new (os) process could cause the emulator to deadlock. This bug affect all emulators with SMP support, and emulators with async thread support on SunOS.

  Own Id: OTP-6241 Aux Id: OTP-3906

- Fprof traces could become truncated for the SMP emulator. This bug has now been corrected.

  Own Id: OTP-6246

- The undocumented functions inet:getiflist/0,1 inet:ifget/2,3 and inet:getif/1 were completely broken on Windows. That has been fixed.

  Own Id: OTP-6255

- Behavior in case of disappeared nodes when using the dist_auto_connect once got changed in R11B-1. The timeouts regarding normal distributed operations is now reverted to the old (pre R11B-1).

  Own Id: OTP-6258 Aux Id: OTP-6200, seq10449

- The bsl and bsr operators could cause the emulator to crash if given invalid arguments. (Thanks to datacompboy and Per Gustafsson.)

  Own Id: OTP-6259

- driver_cancel_timer() could under certain circumstances fail to cancel the timer on the runtime system with SMP support.

  Own Id: OTP-6261

- A call to erlang:system_info(info) could deadlock the runtime system with SMP support.

  Own Id: OTP-6268

#### Improvements and New Features

- Exit signals are now truly asynchronous in the runtime system with SMP support. This simplifies locking in bifs a lot, and makes process termination cheaper.

  Own Id: OTP-6160

- When tracing on the runtime system with SMP support it can be difficult to know when a trace has been delivered to the tracer. A new built in function erlang:trace_delivered/1 has been introduced in order to make it easier to know when the trace has been delivered. See the erlang(3) man page for more information.

  Own Id: OTP-6205 Aux Id: OTP-6269

- Kernel poll support can now be combined with SMP support. Currently the following kernel poll versions exist: /dev/poll, epoll, and kqueue. Linux kpoll has been replaced with epoll. Some time in the future there will also be a kernel poll version using Solaris event ports.

  The "check io" implementation for unix has been completely rewritten. The current kernel poll implementation reduce the amount of system calls needed compared to the old kernel poll implementation.

  When epoll or kqueue is used either poll or select is used as fallback. Previously only poll could be used as fallback. Since select now can be used as fallback, kernel poll support is now also available on newer MacOSX. Note however, when select is used as fallback, the maximum number of file descriptors is limited to FD_SETSIZE.

  Kernel poll support is now enabled by default if /dev/poll, epoll, or kqueue is found when building OTP, i.e. you do not have to pass the --enable-kernel-poll argument to configure. As before, kernel poll is disabled by default in the runtime system. In order to enable it, pass the +Ktrue command line argument to erl.

  Note: configure will refuse to enable kernel poll support on FreeBSD since kqueue have problems with (at least) pipes on all version of FreeBSD that we have tested.

  Own Id: OTP-6222 Aux Id: seq10380

- The erl_ddll module and the code in the emulator have been completely rewritten; several bugs were fixed.

  Own Id: OTP-6234

- The SMP emulator now avoids locking for the following operations (thus making them as fast as in the UP emulator): atom_to_list/1, atom comparison, atom hashing, erlang:apply/3.

  Own Id: OTP-6252

- There are new BIFs erlang:spawn_monitor/1,3, and the new option monitor for spawn_opt/2,3,4,5.

  The observer_backend module has been updated to handle the new BIFs.

  Own Id: OTP-6281

### 1.50 Erts 5.5.1.1

#### Improvements and New Features

- There is now an option read_packets for UDP sockets that sets the maximum number of UDP packets that will be read for each invocation of the socket driver.

  Own Id: OTP-6249 Aux Id: seq10452

### 1.51 Erts 5.5.1

#### Fixed Bugs and Malfunctions

- Complex pattern matching of strings would fail in the 64 bits emulator because of a bug in the loader. (Thanks to Igor Goryachev.)

  Own Id: OTP-6142

- -134217728 div 134217728 and -134217728 rem 134217728 would be calculated incorrectly. abs(-2147483648) could in unlucky circumstances cause a heap overflow, as could size(Binary) when size of the binary was larger than 128Mb.

  Own Id: OTP-6154

- erlang:display/1 displayed erroneous values for negative integers.

  Big integers (both positive and negative) were previously displayed in hexadecimal form while small integers were displayed in decimal form. All integers are now displayed in decimal form.

  NOTE: erlang:display/1 should only be used for debugging.

  Own Id: OTP-6156

- A call to erlang:trace/3 with erroneous flags caused the SMP emulator to deadlock instead of exiting the calling process with badarg.

  Own Id: OTP-6175

- A bug causing the emulator to hang when exiting a process that is exception traced has been fixed.

  Own Id: OTP-6180

- ets:rename/1 could deadlock, or crash the SMP emulator when the table wasn't a named table.

  ets:next/2, and ets:prev/2 could return erroneous results on the SMP emulator.

  Own Id: OTP-6198 Aux Id: seq10392, seq10415

- A memory allocation bug could cause the SMP emulator to crash when a process had executed a receive after with a larger timeout than 10 minutes.

  Own Id: OTP-6199

- The runtime system with SMP support did not slowly adjust its view of time when the system time suddenly changed.

  Timeouts could sometimes timeout too early on the runtime system with SMP support.

  Own Id: OTP-6202

#### Improvements and New Features

- The smp runtime system now automatically detects the number of logical processors on MacOSX (darwin) and OpenBSD.

  The smp runtime system is now built by default on MacOSX (darwin) on x86.

  Own Id: OTP-6119

- The -smp command line argument now take the following options: enable, auto, or disable.

  Especially the -smpauto argument is useful since it starts the Erlang runtime system with SMP support if it is available and more than one logical processor are detected; otherwise, it starts the Erlang runtime system without SMP support. For more information see the erl(1) man page.

  Own Id: OTP-6126

- Increased the reduction cost for sending messages in the SMP emulator so it behaves more like the non-SMP emulator.

  Own Id: OTP-6196

- A port running a dynamically linked-in driver that exits due to the driver being unloaded now exits with exit reason driver_unloaded. Previously the port exited with exit reason -1.

  *** POTENTIAL INCOMPATIBILITY ***

  Own Id: OTP-6204

- Changed name of the erlang:system_info/1 argument scheduler to scheduler_id. This since the scheduler argument so easily could be mixed up with the schedulers argument (both returning integers).

  *** POTENTIAL INCOMPATIBILITY ***

  Own Id: OTP-6208

- The changes below were made by Mikael Pettersson, HiPE.

  HiPE runtime system:

  Reduce overheads in the HiPE runtime system's BIF glue code.

  Fix bug when exceptions are thrown from BEAM to HiPE.

  Support SPARC on Linux.

  Support x86 on FreeBSD.

  Floating-point exceptions:

  Reduce overheads in checking results of floating-point operations.

  Minor bug fix in SSE2 floating-point exception handling.

  Support SSE2 floating-point exceptions on 32-bit x86 machines.

  Make FP exceptions work in the SMP runtime system on FreeBSD/x86.

  Support floating-point exceptions on SPARCs running Linux.

  Runtime system:

  Minor scheduler optimisation in the non-SMP runtime system.

  Substantial reduction of I/O thread overheads in the SMP runtime system if the separate timer thread is used. (In R11B-1, the separate timer thread is not used.)

  Own Id: OTP-6211

### 1.52 ERTS 5.5

#### Fixed Bugs and Malfunctions

- Previously unlink/1 and erlang:demonitor/2 behaved completely asynchronous. This had one undesirable effect, though. You could never know when you were guaranteed not to be affected by a link that you had unlinked or a monitor that you had demonitored.

  The new behavior of unlink/1 and erlang:demonitor/2 can be viewed as two operations performed atomically. Asynchronously send an unlink signal or a demonitor signal, and ignore any future results of the link or monitor.

  NOTE: This change can cause some obscure code to fail which previously did not. For example, the following code might hang:

                  Mon = erlang:monitor(process, Pid),
                  %% ...
                  exit(Pid, bang),
                  erlang:demonitor(Mon),
                  receive
                      {'DOWN', Mon , process, Pid, _} -> ok
                  %% We were previously guaranteed to get a down message
                  %% (since we exited the process ourself), so we could
                  %% in this case leave out:
                  %% after 0 -> ok
                  end,

  *** POTENTIAL INCOMPATIBILITY ***

  Own Id: OTP-5772

- Two bugs fixed: If the environment variable ERL_FLAGS was set, its contents would be appended to the end of the command line even if the command line had an -extra options. Changed to place the options from ERL_FLAGS just before -extra. Also, the -smp and -hybrid flags no longer have any effect if placed after -extra.

  Own Id: OTP-6054

#### Improvements and New Features

- The documentation for writing drivers in the ERTS User's Guide has been expanded and updated.

  Own Id: OTP-5192

- The andalso and orelse operators are now allowed to be used in guards. That also applies to match specifications.

  Own Id: OTP-5894 Aux Id: OTP-5149

- There is a new trace match spec function {exception_trace} and a corresponding trace message exception_from that can be used to trace on any exit from a function, both normal function return and exception return. See the documentation for details.

  The return_to trace message is now also generated when the execution returns to a function due to catching an exception.

  Own Id: OTP-5956

- Erlang runtime system with SMP (symmetric multi processing) support.

  The runtime system with SMP support is in this release focused on stability and there are a number of steps with optimizations to follow before it will take full advantage of multi processor systems. The released system is however truly multi threaded and you will notice increased performance for many applications already. We recommend that you evaluate your application on the SMP version of the runtime system and wait for some more optimizations before you use it in a real product. You will then discover if there are any problems in your application that needs to be fixed in order for it to work properly in a multi threaded environment. More optimized versions of the runtime system with SMP support will be included in the R11B maintenance releases.

  The SMP enabled runtime system will be started if the -smp command line argument is passed to the erl command. In order to make use of more than one processor core, multiple scheduler threads are used. By default, the number of scheduler threads will equal the number of processor cores. The number of scheduler threads can be set with the +S command line argument. For more information see the erl(1) man page.

  A runtime system with SMP support is by default built on the following platforms if posix threads, and a gcc compiler of at least version 2.95 is found:

  - Linux with at least kernel version 2.6 and the Native POSIX Thread Library on x86, x86_64, and 32-bits PowerPC.

  - Solaris of at least version 8 on 32-bits SPARC-V9.

  - MacOSX of at least version 10.4 (Darwin 8.0) on 32-bits PowerPC.

  The runtime system with SMP support is known not to build on:

  - Windows.

  - Linux with kernel versions less than 2.4, or without the Native POSIX Thread Library.

  - Other hardware platforms than x86, x86_64, 32-bits SPARC-V9 and 32-bits PowerPC.

  Windows will be supported in a future release.

  The runtime system with SMP support might build on other operating systems in combination with supported hardware. In order to force a build of a runtime system with SMP support, pass the --enable-smp-support command line argument to configure. Note, however, that it is not enough that it builds. The underlying thread library and operating system has to provide SMP support as well. If the thread library does not distribute scheduler threads over multiple processor cores then the runtime system will only seemingly provide SMP support. If the runtime system is not built by default on a specific platform, we have not tested it on that platform.

  NOTE: The design of SMP support for drivers is ongoing. There will probably be incompatible driver changes (only affecting drivers run on the runtime system with SMP support) released as patches for R11B.

  Potential incompatibility: Previously, specific driver call-backs were always called from the same thread. This is not true in the runtime system with SMP support. Calls to call-backs will be made from different threads, e.g., two consecutive calls to exactly the same call-back can be made from two different threads. This will in most cases not be a problem. All calls to call-backs are synchronized, i.e., only one call-back will be called at a time.

  In the future the default behavior will probably be the following: Calls to call-backs will, as now, be made from different threads. Calls to call-backs in the same driver instance will be synchronized. It will probably be possible to configure so that all calls to call-backs in all driver instances of a specific driver type will be synchronized. It may be possible to configure so that all calls to call-backs of a driver instance or a of a specific driver type will be made from the same thread.

  Parallelism in the Erlang code executed is a necessity for the Erlang runtime system to be able to take advantage of multi-core or multi-processor hardware. There need to be at least as many Erlang processes runnable as processor cores for the Erlang runtime system to be able to take advantage of all processor cores.

  An Erlang runtime system with SMP support with only one Erlang process runnable all the time will almost always be slower than the same Erlang runtime system without SMP support. This is due to thread synchronization overhead.

  Known major bottleneck in the Erlang runtime system:

  - Currently the I/O system uses one "big lock", i.e. only one thread can do I/O at a time (with the exception of async threads and threads created by users own linked-in drivers). This is high on the list of things to optimize. Note, code that does not do I/O can be executed at the same time as one thread does I/O.

  Some pitfalls which might cause Erlang programs that work on the non-SMP runtime system to fail on the SMP runtime system:

  - A newly spawned process will often begin executing immediately. Code that expects that the parent process will be able to execute for a while before the child process begins executing is likely to fail.

  - High priority processes could previously provide mutual exclusion (bad programming style) by preventing normal and low priority processes from being run. High priority processes cannot be used this way to provide mutual exclusion.

  - erlang:yield() could be used to provide some kind of temporary mutual exclusion (also bad programming style). erlang:yield() cannot be used to provide any kind of mutual exclusion.

  - Obscure pitfall, only if a process being traced also sends normal messages to the tracer:
    The order between trace messages and normal messages is undefined. I.e. the order between normal messages sent from a tracee to a tracer and the trace messages generated from the same tracee to the same tracer is undefined. The internal order of normal messages and the internal order of trace messages will, of course, be preserved as before.

  The kernel poll feature is currently not supported by the runtime system with SMP support. It will probably be supported in a future release.

  *** POTENTIAL INCOMPATIBILITY ***

  Own Id: OTP-6006 Aux Id: OTP-6095

- Linked-in driver modifications.

  - Linked-in drivers must be recompiled.

  - The refc field in the ErlDrvBinary type has been removed. The reference count can be accessed via API functions. For more information see the erl_driver(1) man page.

  *** POTENTIAL INCOMPATIBILITY ***

  Own Id: OTP-6095 Aux Id: OTP-6006

### 1.53 ERTS 5.4.13

#### Fixed Bugs and Malfunctions

- Large files (more than 2 GBytes) are now handled on Solaris 8.

  Own Id: OTP-5849 Aux Id: seq10157

- A failing bit syntax construction could fail with the PREVIOUS exception reason that had occurred in the process (instead of with badarg).

  Own Id: OTP-5911

- When building OTP, the Kernel application was built in both the primary and secondary bootstrap steps, which would cause problems if OTP including its bootstrap is checked into a version control system (such as CVS). (Thanks to Sebastian Strollo.)

  Own Id: OTP-5921

- binary_to_term(<<131,109,255,255,255,255) and similar expressions used to crash the emulator instead of causing a badarg exception. (Thanks to Matthias Lang.)

  Own Id: OTP-5933

- erlang:hibernate/3 could sometimes crash the emulator when no heap was needed.

  Own Id: OTP-5940

- Execution of match specs could under rare circumstances cause the emulator to dump core.

  Execution of match specs could cause memory leaks in the hybrid emulator.

  Own Id: OTP-5955

- A bug in erlang:trace_info/2 when getting info for a function in a deleted module resulting in an emulator crash, has been corrected.

  Own Id: OTP-5957

- Different (and old) config.guess files in the ERTS and Erl_Interface applications would cause build problems on the new Intel-based iMacs. (Thanks to Sebastion Strollo.)

  Own Id: OTP-5967

- pthread header and library mismatch on Linux systems (at least some SuSE and Debian) with both NPTL and Linuxthreads libraries installed.

  Own Id: OTP-5981

#### Improvements and New Features

- The driver_set_timer did not change the previous timeout if called a second time. Now it works as specified, changing the timeout.

  Own Id: OTP-5942

- The undocumented {packet,http} option (for the gen_tcp module) did not not work correctly when there were multiple continuation lines. (Thanks to Per Hedeland.)

  Own Id: OTP-5945

- The setuid_socket_wrap program was corrected to work for C compilers that treat the char type as unsigned. (Thanks to Magnus Henoch.)

  Own Id: OTP-5946

### 1.54 ERTS 5.4.12

#### Fixed Bugs and Malfunctions

- Fixed a minor build problem on Windows.

  Own Id: OTP-5819 Aux Id: OTP-5382 OTP-5540 OTP-5577

- The delay_send option for gen_tcp was broken on Windows.

  Own Id: OTP-5822

- If there were user-defined variables in the boot script, and their values were not provided using the -boot_var option, the emulator would refuse to start with a confusing error message. Corrected to show a clear, understandable message.

  The prim_file module was modified to not depend on the lists module, to make it possible to start the emulator using a user-defined loader. (Thanks to Martin Bjorklund.)

  Own Id: OTP-5828 Aux Id: seq10151

#### Improvements and New Features

- The HiPE compiler identifies more leaf functions, giving slightly faster code.

  Corrected problems in HiPE's coalescing register allocating that would cause it to fail when compiling very large functions (e.g. some of parse modules in the Megaco application).

  Own Id: OTP-5853

### 1.55 ERTS 5.4.11

#### Fixed Bugs and Malfunctions

- Timers could sometimes timeout too early. This bug has now been fixed.

  Automatic cancellation of timers created by erlang:send_after(Time,pid(),Msg) and erlang:start_timer(Time,pid(),Msg) has been introduced. Timers created with the receiver specified by a pid, will automatically be cancelled when the receiver exits. For more information see the erlang(3) man page.

  In order to be able to maintain a larger amount of timers without increasing the maintenance cost, the internal timer wheel and bif timer table have been enlarged.

  Also a number of minor bif timer optimizations have been implemented.

  Own Id: OTP-5795 Aux Id: OTP-5090, seq8913, seq10139, OTP-5782

- erlang:monitor(process,Pid) hanged if Pid referred to a process on a non-existing node with the same nodename as the nodename of node on which the call was made. This bug has now been fixed.

  Own Id: OTP-5827

#### Improvements and New Features

- By setting Unix environment variables, the priority for the emulator can be lowered when it is writing crash dumps and the time allowed for finishing writing a crash dump can be set to a certain number of seconds. See the documentation for erl in the ERTS application. (Also, a few other previously undocumented environment variables are now documented.)

  Own Id: OTP-5818

- Documentation improvements:

  - documentation for erlang:link/1 corrected

  - command line flag -code_path_cache added

  - erl command line flags clarifications

  - net_kernel(3) clarifications

  Own Id: OTP-5847

### 1.56 ERTS 5.4.10

#### Fixed Bugs and Malfunctions

- -D_GNU_SOURCE is now always passed on the compile command line on linux. This in order to ensure that all included system headers see _GNU_SOURCE defined.

  _GNU_SOURCE is now also defined on linux in configure when looking for features.

  Some minor (harmless) configure bugs were also fixed.

  Own Id: OTP-5749

- Some compiler warnings and Dialyzer warnings were eliminated in the Tools application.

  When tracing to a port (which fprof does), there could be fake schedule out/schedule in messages sent for a process that had exited.

  Own Id: OTP-5757

#### Improvements and New Features

- The BIFs iolist_size/1 and iolist_to_binary/1 has been added.

  The BIF list_to_existing_atom/1 has been added.

  Minor bug fix: The exception reason could be changed to error inside nested try/catch constructs if the erlang:raise/3 BIF was called with an empty stacktrace. (Calling erlang:raise/3 with an empty stacktrace is NOT recommended.)

  Minor bugfix: On Windows, file:open/2 will now return the documented error reason {error,eisdir} if the filename refers to a directory (it used to return {error,eacces}).

  The message in the documentation for erlang:system_monitor/2, description of busy_dist_port, was corrected.

  Own Id: OTP-5709 Aux Id: seq10100

- The previously undocumented and UNSUPPORTED zlib module has been updated in an incompatible way and many bugs have been corrected. It is now also documented.

  *** POTENTIAL INCOMPATIBILITY ***

  Own Id: OTP-5715

- New socket options priority and tos for platforms that support them (currently only Linux).

  Own Id: OTP-5756

- Only the emulator is now linked with termcap library in order to decrease library dependencies for other otp programs.

  Own Id: OTP-5758

### 1.57 ERTS 5.4.9.2

#### Fixed Bugs and Malfunctions

- The native resolver has gotten an control API for extended debugging and soft restart. It is: inet_gethost_native:control(Control)
  Control = {debug_level,Level} | soft_restart
  Level = integer() in the range 0-4.

  Own Id: OTP-5751 Aux Id: EABln25013

### 1.58 ERTS 5.4.9.1

#### Improvements and New Features

- On VxWorks, epmd did not handle file descriptors with higher numbers than 63. Also, if epmd should get a file descriptor with a number >= FD_SETSIZE, it will close a the file descriptor and write a message to the log (instead of mysteriously fail); the Erlang node that tried to register will fail with a duplicate_name error (unfortunately, epmd has no way to indicate to the Erlang node why the register attempt failed).

  Own Id: OTP-5716 Aux Id: seq10070

### 1.59 ERTS 5.4.9

#### Fixed Bugs and Malfunctions

- Timezone data is now initialized better. (was a problem at least on NetBSD 2.0.2) Thanks to Rich Neswold.

  Own Id: OTP-5621

- The hybrid-heap emulator ('erl -hybrid') is much more stable. We have corrected all known bugs that caused it to dump core while running our test suites.

  Own Id: OTP-5634

- Fixed rare memory leaks in erlang:demonitor/1 when distributed monitors were removed.

  Own Id: OTP-5692

- Processes were sometimes unnecessarily garbage collected when terminating. These unnecessary garbage collections have now been eliminated.

  Own Id: OTP-5693

#### Improvements and New Features

- The c:i/0 function will now run in a paged mode if there are more than 100 processes in the system. (Thanks to Ulf Wiger.)

  erlang:system_info(process_count) has been optimized and does now return exactly the same value as length(processes()). Previously erlang:system_info(process_count) did not include exiting processes which are included in length(processes()).

  The +P flag for erl, which sets the maximum number of processes allowed to exist at the same, no longer accepts values higher than 134217727. (You will still probably run out of memory before you'll be able to reach that limit.)

  Own Id: OTP-5645 Aux Id: seq9984

- The term-building driver functions driver_output_term() and driver_send_term() have been updated:

  The ERL_DRV_FLOAT type has been added.

  For the ERL_DRV_BINARY type, the length and offset are now validated against the length of the driver binary.

  The ERL_DRV_PID type is now implemented (it was documented, but not implemented).

  Own Id: OTP-5674

### 1.60 ERTS 5.4.8

#### Fixed Bugs and Malfunctions

- ets:delete/1 now allows other Erlang process to run when a large table is being deleted.

  Own Id: OTP-5572

- A bug regarding tcp sockets which results in hanging gen_tcp:send/2 has been corrected. To encounter this bug you needed one process that read from a socket, one that wrote more date than the reader read out so the sender got suspended, and then the reader closed the socket. (Reported and diagnosed by Alexey Shchepin.)

  Corrected a bug in the (undocumented and unsupported) option {packet,http} for gen_tcp. (Thanks to Claes Wikstrom and Luke Gorrie.)

  Updated the documentation regarding the second argument to gen_tcp:recv/2, the Length to receive.

  Own Id: OTP-5582 Aux Id: seq9839

- Erlang/OTP will now build on Mac OS X 10.4 "Tiger" (the problem was that 10.4 has a partially implemented poll() function that can't handle devices). Also, on Mac OS X 10.3 "Panther", Erlang/OTP will now use select() instead of poll() (because poll() on Mac OS X 10.3 is implemented using select()).

  Own Id: OTP-5595

- A bug in the file driver when opening a file in compressed mode, and the returned allocated pointer from the compressing library was in very high memory (>= 2GB), causing e.g. file:read/2 to return {error,ebadf}, has been corrected.

  Own Id: OTP-5618

#### Improvements and New Features

- The new fun M:F/A construct creates a fun that refers to the latest version of M:F/A. This syntax is meant to replace tuple funs {M,F} which have many problems.

  The new type test is_function(Fun,A) (which may be used in guards) test whether Fun is a fun that can be applied with A arguments. (Currently, Fun can also be a tuple fun.)

  Own Id: OTP-5584

- In the HiPE application, there's a new experimental register allocator (optimistic coalescing), and the linear scan register allocator is now also available on ppc. Plus lots of cleanups.

  Minor hybrid heap corrections.

  The maximum size of a heap used to be artificially limited so that the size of a heap would fit in 28 bits; that limitation could cause the emulator to terminate in a garbage collection even if there still was available memory. Now the largest heap size for a 32 bit CPU is 1,699,221,830 bytes. (Thanks to Jesper Wilhelmsson.)

  Also removed the undocumented +H emulator option.

  Own Id: OTP-5596

### 1.61 ERTS 5.4.7

#### Fixed Bugs and Malfunctions

- to_erl could close unexpectedly on Linux systems. Also, output from the emulator could be lost. Corrected.

  Own Id: OTP-5561

#### Improvements and New Features

- The cpu_timestamp option for erlang:trace/3 is now also supported on Linux.

  Own Id: OTP-5532 Aux Id: seq9813

- The last known werl window size/position is now saved correctly when werl is stopped with the window minimized. A problem with the placement not being saved if the emulator is halted or stopped from the JCL menu has also been fixed.

  Own Id: OTP-5544 Aux Id: OTP-5522

### 1.62 ERTS 5.4.6

#### Fixed Bugs and Malfunctions

- Some math libraries do not always throw floating-point exceptions on errors. In order to be able to use these libraries, floating-point errors are now more thoroughly checked.

  Misc floating-point fixes for Linux and MacOSX.

  Own Id: OTP-5467

- An internal buffer was sometimes not cleared which caused garbage to appear in error messages sent to the error logger.

  errno was sometimes clobbered which caused erroneous error reports about poll() errors.

  Only emulators on unix platforms were affected by these bugs.

  Own Id: OTP-5492

- The ethread library now works on OpenBSD.

  Own Id: OTP-5515

- Corrected a bug in the (undocumented and unsupported) option {packet,http} for gen_tcp. (Thanks to Claes Wikstrom and Luke Gorrie.)

  Own Id: OTP-5519

#### Improvements and New Features

- binary_to_term/1 could cause the emulator to crash when given invalid pids or funs.

  Own Id: OTP-5484 Aux Id: seq9801

- Some more stability problems were fixed in the hybrid-heap emulator.

  Own Id: OTP-5489

- After werl was closed with the window minimized, it was not possible to restart werl with an open window. A temporary solution has so far been implemented that restores the initial window settings every time werl is started.

  Own Id: OTP-5522

### 1.63 ERTS 5.4.5

#### Fixed Bugs and Malfunctions

- If a process had node links (created by monitor_node/2), executing process_info(Pid,memory) for that process would crash the emulator.

  Own Id: OTP-5420

- Minor corrections to the help text printed by erlc -help. The documentation for erlc was also slightly updated.

  Own Id: OTP-5428

- 32-bit words were used for offsets in the garbage collector. This caused the emulator to crash on 64-bit machines when heaps were moved more than 4 GB during garbage collection.

  Own Id: OTP-5430

- is_boolean(42.5) failed to load if optimization was explicitly turned off.

  Own Id: OTP-5448

- If there was a call to Module:foo/X from any loaded module, the returned by M:module_info(exports) would always include {foo,X} (even though Module:foo/X if was not defined).

  Own Id: OTP-5450 Aux Id: seq9722

#### Improvements and New Features

- The c option for the +B flag has been introduced which makes it possible to use Ctrl-C (Ctrl-Break on Windows) to interrupt the shell process rather than to invoke the emulator break handler. All new +B options are also supported on Windows (werl) as of now. Furthermore, Ctrl-C on Windows has now been reserved for copying text (what Ctrl-Ins was used for previously). Ctrl-Break should be used for break handling. Lastly, the documentation of the system flags has been updated.

  Own Id: OTP-5388

### 1.64 ERTS 5.4.4

#### Fixed Bugs and Malfunctions

- The function erlang:float/1 can now be used in match specifications and is recognized by dbg:fun2ms/1 and ets:fun2ms/1. This addition is part of the work to "harmonize" match specification guards with Erlang guards.

  Own Id: OTP-5297 Aux Id: OTP-4927

- The register/2 BIF would return true even if the second argument was not a pid for living process. Corrected to cause an exception.

  Own Id: OTP-5324 Aux Id: seq9698

- In the 'bag' type of ets tables, elements having the same key were supposed to be order in insertion order. The would be wrong if a rehash occurred.

  Own Id: OTP-5340 Aux Id: seq9704

- Linked in drivers in the Crypto and Asn1 applications are now compiled with the -D_THREAD_SAFE and -D_REENTRANT switches on unix when the emulator has thread support enabled.

  Linked in drivers on MacOSX are not compiled with the undocumented -lbundle1.o switch anymore. Thanks to Sean Hinde who sent us a patch.

  Linked in driver in Crypto, and port programs in SSL, now compiles on OSF1.

  Minor makefile improvements in Runtime_Tools.

  Own Id: OTP-5346

- Fixed a bug in the hybrid heap in distributed send operations.

  Own Id: OTP-5361

- A BIF erlang:raise/3 has been added. See the manual for details. It is intended for internal system programming only, advanced error handling.

  Own Id: OTP-5376 Aux Id: OTP-5257

- Mikael Pettersson (HiPE) corrected a few bugs in the emulator that caused problems when compiled with the experimental gcc-4.0.0.

  Own Id: OTP-5386

#### Improvements and New Features

- Minor update of the internal documentation of the epmd protocol.

  The listen port of epmd has now been registered at IANA: http://www.iana.org/assignments/port-numbers.

  Own Id: OTP-5234

- run_erl.c now works on Mac OS X and FreeBSD.

  Own Id: OTP-5384

- A few bugs were corrected in the HiPE application.

  Own Id: OTP-5385

### 1.65 ERTS 5.4.3

#### Fixed Bugs and Malfunctions

- Font and color preferences for werl.exe now can be saved even after the first time you run werl.exe. The window position and size is also saved. Patch from James Hague who did all the hard work.

  Own Id: OTP-5250

- OTP archive libraries, e.g. the erl_interface library, on MacOSX could not be used without first rerunning ranlib on them. This bug has now been fixed.

  Own Id: OTP-5274

- Bugs in erlang:hash/2 and erlang:phash/2 on 64-bit platforms have been fixed.

  Own Id: OTP-5292

#### Improvements and New Features

- Corrected a crash in the 64-bits emulator.

  Corrected a problem in the hybrid heap emulator.

  In the chapter about the abstract format in the ERTS User's Guide, updated the last section about how the abstract format is stored in BEAM files.

  Own Id: OTP-5262

- The maximum number of concurrent threads in the internal ethread thread package has been limited to 2048.

  Own Id: OTP-5280

### 1.66 ERTS 5.4.2.1

#### Improvements and New Features

- If Erlang/OTP was installed in a short directory name, such as C:\Program\erl5.4.2, the emulator would not start.

  Own Id: OTP-5254

### 1.67 ERTS 5.4.2

#### Fixed Bugs and Malfunctions

- If one used select/3 and select/1 on a non-fixed ETS table and deleted objects simultaneously, the emulator could crash. Note that the result of such simultaneous operations on tables that are not in a fixed state is still undefined, but the emulator crash is, needless to say, fixed.

  Own Id: OTP-5209 Aux Id: seq9198

- Arithmetic with big numbers could crash the emulator.

  The HiPE native code compiler and run-time code in the emulator has been updated. (Note: Native code is still not supported.)

  Eliminated a few bugs that could crash the hybrid emulator (which is not supported).

  Own Id: OTP-5233 Aux Id: seq9587

### 1.68 ERTS 5.4.1

#### Fixed Bugs and Malfunctions

- The ethread library was unnecessarily rebuilt multiple times during the build process, also a debug version of the library was build during the install phase. These unnecessary builds have now been removed. Note, the content of the installed Erlang/OTP system is not effected at all by this change.

  Own Id: OTP-5203

- The emulator could fail to clear the memory segment cache. This could potentially cause memory allocation to unnecessarily fail when memory usage was close to its maximum. This bug has now been fixed.

  Own Id: OTP-5211

- std_alloc (std short for standard) was sometimes called def_alloc (def short for default). std_alloc is now everywhere referred to as std_alloc.

  Own Id: OTP-5216

- A documentation bug has been corrected in the erts_alloc(3) documentation. It was stated that some of the memory allocators present were by default disabled. This is true for Erlang/OTP R9C, but is not true for Erlang/OTP R10B. In R10B all memory allocators present are enabled by default.

  Own Id: OTP-5217

#### Improvements and New Features

- The emulator now close all open files and sockets immediately after receiving an USR1 signal. This causes the emulator to unregister at epmd as early as possible.

  Own Id: OTP-5221 Aux Id: OTP-4985, seq9514

- Try/catch support in the emulator slightly updated.

  Own Id: OTP-5229