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</header>
<p>This document describes the changes made to the ERTS application.</p>
+<section><title>Erts 5.8</title>
+
+ <section><title>Fixed Bugs and Malfunctions</title>
+ <list>
+ <item>
+ <p>
+ Driver threads, such as async threads, using <seealso
+ marker="erl_driver#ErlDrvPDL">port data locks</seealso>
+ peeked at the port status field without proper locking
+ when looking up the driver queue.</p>
+ <p>
+ Own Id: OTP-8475</p>
+ </item>
+ <item>
+ <p>
+ The use of <c>mmap()</c> was unnecessarily disabled when
+ cross compiling.</p>
+ <p>
+ The <c>configure</c> arguments <c>--with-ssl</c>, and
+ <c>--with-odbc</c> refused to accept libraries outside of
+ <c>$erl_xcomp_sysroot</c> when cross compiling for no
+ good reason.</p>
+ <p>
+ The <c>configure</c> argument <c>--with-odbc</c> didn't
+ handle the value <c>yes</c> correct.</p>
+ <p>
+ The <c>configure</c> arguments <c>--with-odbc</c>, and
+ <c>--without-odbc</c> have also been added to the
+ configure help.</p>
+ <p>
+ (Thanks to Steve Vinoski for reporting these issues)</p>
+ <p>
+ Own Id: OTP-8484</p>
+ </item>
+ <item>
+ <p>
+ A call to the BIF <c>unregister(RegName)</c> when a port
+ had the name <c>RegName</c> registered in the runtime
+ system without SMP support caused a runtime system crash.
+ (Thanks to Per Hedeland for the bugfix and test case.)</p>
+ <p>
+ Own Id: OTP-8487</p>
+ </item>
+ <item>
+ <p>
+ The runtime system crashed if fewer logical processors
+ were found than reported by <c>sysconf(
+ SC_NPROCESSORS_CONF)</c>.</p>
+ <p>
+ Own Id: OTP-8549</p>
+ </item>
+ <item>
+ <p>
+ Fix memory management bug causing crash of non-SMP
+ emulator with async threads enabled. The bug did first
+ appear in R13B03.</p>
+ <p>
+ Own Id: OTP-8591 Aux Id: seq11554 </p>
+ </item>
+ <item>
+ <p>
+ Port locks could be prematurely destroyed.</p>
+ <p>
+ Own Id: OTP-8612</p>
+ </item>
+ <item>
+ <p>The <c>empd</c> program could loop and consume 100%
+ CPU time if an unexpected error ocurred in
+ <c>listen()</c> or <c>accept()</c>. Now <c>epmd</c> will
+ terminate if a non-recoverable error occurs. (Thanks to
+ Michael Santos.)</p>
+ <p>
+ Own Id: OTP-8618</p>
+ </item>
+ <item>
+ <p>
+ When kernel poll has been enabled, a livelock could in
+ rare circumstances occur. Problem reported by Chetan
+ Ahuja, fix by Mikael Pettersson.</p>
+ <p>
+ Own Id: OTP-8632</p>
+ </item>
+ <item>
+ <p>
+ Windows: Closing port of program that stalled without
+ reading all data could deadlock scheduler thread.</p>
+ <p>
+ Own Id: OTP-8641</p>
+ </item>
+ <item>
+ <p>
+ 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.</p>
+ <p>
+ Own Id: OTP-8654</p>
+ </item>
+ <item>
+ <p>
+ Missing memory barriers in <c>erts_poll()</c> could cause
+ the runtime system to hang indefinitely.</p>
+ <p>
+ Own Id: OTP-8658</p>
+ </item>
+ <item>
+ <p>
+ <c>ethr_rwmutex_tryrlock()</c> 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)</p>
+ <p>
+ Own Id: OTP-8662</p>
+ </item>
+ <item>
+ <p>
+ Extreme combinations of register/unregister in a highly
+ parallell SMP application could crash the VM. The error
+ is corrected.</p>
+ <p>
+ Own Id: OTP-8663</p>
+ </item>
+ <item>
+ <p>
+ On Windows, files are now opened with FILE_SHARE_DELETE
+ to get closer to Unix semantics.</p>
+ <p>
+ Own Id: OTP-8667</p>
+ </item>
+ <item>
+ <p>
+ <c>erlang:system_info(multi_scheduling)</c> sometimes
+ erroneously returned <c>enabled</c> when it should have
+ returned <c>blocked</c>.</p>
+ <p>
+ Own Id: OTP-8675</p>
+ </item>
+ <item>
+ <p>
+ Fix bug causing <c>erlang:decode_packet</c> and
+ <c>enif_make_string</c> to generate faulty strings with
+ negative character values for ascii values larger than
+ 127. (Thanks to Paul Guyot)</p>
+ <p>
+ Own Id: OTP-8685</p>
+ </item>
+ <item>
+ <p>
+ <c>open_port/2</c> with the <c>spawn</c> and
+ <c>spawn_executable</c> options can include an
+ <c>{env,Env}</c> option. In some cases unsetting
+ variables would not work on Unix (typically if more
+ variables were unset than were actually present in the
+ environment).</p>
+ <p>
+ Own Id: OTP-8701</p>
+ </item>
+ </list>
+ </section>
+
+
+ <section><title>Improvements and New Features</title>
+ <list>
+ <item>
+ <p>
+ 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.</p>
+ <p>
+ Own Id: OTP-8086 Aux Id: seq11333 </p>
+ </item>
+ <item>
+ <p>
+ The module binary from EEP31 (and EEP9) is implemented.</p>
+ <p>
+ Own Id: OTP-8217</p>
+ </item>
+ <item>
+ <p>
+ New NIF API function <c>enif_make_new_binary</c></p>
+ <p>
+ Own Id: OTP-8474</p>
+ </item>
+ <item>
+ <p>
+ The guard BIF <c>is_boolean/1</c> (introduced in R10B)
+ has now been included in the lists of BIFs allowed in
+ guards in the Reference Manual.</p>
+ <p>
+ Own Id: OTP-8477</p>
+ </item>
+ <item>
+ <p>
+ Added function <c>zip:foldl/3</c> to iterate over zip
+ archives.</p>
+ <p>
+ Added functions to create and extract escripts. See
+ <c>escript:create/2</c> and <c>escript:extract/2</c>.</p>
+ <p>
+ The undocumented function <c>escript:foldl/3</c> has been
+ removed. The same functionality can be achieved with the
+ more flexible functions <c>escript:extract/2</c> and
+ <c>zip:foldl/3</c>.</p>
+ <p>
+ Record fields has been annotated with type info. Source
+ files as been adapted to fit within 80 chars and trailing
+ whitespace has been removed.</p>
+ <p>
+ Own Id: OTP-8521</p>
+ </item>
+ <item>
+ <p>A regular expression with many levels of parenthesis
+ could cause a buffer overflow. That has been corrected.
+ (Thanks to Michael Santos.)</p>
+ <p>
+ Own Id: OTP-8539</p>
+ </item>
+ <item>
+ <p>
+ <c>erlang:decode_packet(httph_bin,..)</c> 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 <c>packet</c> option did not suffer
+ from this bug.</p>
+ <p>
+ Own Id: OTP-8548</p>
+ </item>
+ <item>
+ <p>New NIF features:</p> <list><item> Send messages from
+ a NIF, or from thread created by NIF, to any local
+ process (<c>enif_send</c>) </item><item> Store terms
+ between NIF calls (<c>enif_alloc_env</c>,
+ <c>enif_make_copy</c>) </item><item> Create binary terms
+ with user defined memory management
+ (<c>enif_make_resource_binary</c>) </item></list> <p>And
+ some incompatible changes made to the API. For more
+ information see the warning text in <seealso
+ marker="erl_nif">erl_nif(3)</seealso>.</p>
+ <p>
+ *** POTENTIAL INCOMPATIBILITY ***</p>
+ <p>
+ Own Id: OTP-8555</p>
+ </item>
+ <item>
+ <p>If the '<c>fop</c>' 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.)</p>
+ <p>
+ Own Id: OTP-8559</p>
+ </item>
+ <item>
+ <p>When defining macros the closing right parenthesis
+ before the dot is now mandatory.</p>
+ <p>
+ *** POTENTIAL INCOMPATIBILITY ***</p>
+ <p>
+ Own Id: OTP-8562</p>
+ </item>
+ <item>
+ <p>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:</p>
+ <list><item><p>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</p></item>
+ <item><p>Explicitly importing a function having a name
+ clashing with the name of an autoimported BIF that was
+ present (and autoimported) before OTP R14A</p></item>
+ <item><p>Using any form of the old compiler directive
+ <c>nowarn_bif_clash</c></p></item> </list> <p>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,</p> <p>To resolve clashes, you
+ can either use the explicit module name <c>erlang</c> to
+ call the BIF, or you can remove the auto-import of that
+ specific BIF by using the new compiler directive
+ <c>-compile({no_auto_import,[F/A]}).</c>, which makes all
+ calls to the local or imported function without explicit
+ module name pass without warnings or errors.</p> <p>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 <c>nowarn_bif_clash</c> compiler
+ directive, might need changing to be accepted by the
+ compiler.</p>
+ <p>
+ *** POTENTIAL INCOMPATIBILITY ***</p>
+ <p>
+ Own Id: OTP-8579</p>
+ </item>
+ <item>
+ <p>
+ A bug in re that could cause certain regular expression
+ matches never to terminate is corrected. (Thanks to
+ Michael Santos and Gordon Guthrie.)</p>
+ <p>
+ Own Id: OTP-8589</p>
+ </item>
+ <item>
+ <p>The erlang:open_port spawn and spawn_executable
+ directives can include an <c>{env,Env}</c> directive to
+ set up environment variables for the spawned process. A
+ bug prevented applications from using <c>{env,Env}</c> to
+ set an environment variable whose value ended with a
+ '<c>=</c>' (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.)</p>
+ <p>
+ Own Id: OTP-8614</p>
+ </item>
+ <item>
+ <p><c>receive</c> 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
+ <c>gen_server:call()</c>. (See <c>gen:do_call/4</c> for
+ an example of a receive statement that will be
+ optimized.)</p>
+ <p>
+ Own Id: OTP-8623</p>
+ </item>
+ <item>
+ <p>
+ The functions file:advise/4 and file:datasync/1 have been
+ added. (Thanks to Filipe David Manana.)</p>
+ <p>
+ Own Id: OTP-8637</p>
+ </item>
+ <item>
+ <p>
+ New NIF API functions: <c>enif_make_atom_len</c>,
+ <c>enif_make_existing_atom_len</c>,
+ <c>enif_make_string_len</c>, <c>enif_get_atom_length</c>,
+ <c>enif_get_list_length</c>, <c>enif_is_list</c>,
+ <c>enif_is_tuple</c> (by Tuncer Ayaz)</p>
+ <p>
+ Own Id: OTP-8640</p>
+ </item>
+ <item>
+ <p>
+ 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.</p>
+ <p>
+ Own Id: OTP-8659</p>
+ </item>
+ <item>
+ <p>
+ The number of spinlocks used when implementing atomic
+ fall-backs when no native atomic implementation is
+ available has been increased from 16 to 1024.</p>
+ <p>
+ Own Id: OTP-8660</p>
+ </item>
+ <item>
+ <p>
+ Writer preferred pthread read/write locks has been
+ enabled on Linux.</p>
+ <p>
+ Own Id: OTP-8661</p>
+ </item>
+ <item>
+ <p>
+ The runtime system will by default bind schedulers to
+ logical processors using the <c>default_bind</c> 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. </p>
+ <p>
+ <em>NOTE:</em> 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 <seealso
+ marker="erl#+sbt">+sbtu</seealso> command line argument,
+ or by invoking <seealso
+ marker="erlang#system_flag_scheduler_bind_type">erlang:system_flag(scheduler_bind_type,
+ unbound)</seealso>.</p>
+ <p>
+ Own Id: OTP-8666</p>
+ </item>
+ <item>
+ <p>
+ 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.</p>
+ <p>
+ *** POTENTIAL INCOMPATIBILITY ***</p>
+ <p>
+ Own Id: OTP-8669 Aux Id: OTP-8579 </p>
+ </item>
+ <item>
+ <p>
+ 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.</p>
+ <p>
+ Own Id: OTP-8670</p>
+ </item>
+ <item>
+ <p>
+ 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.</p>
+ <p>
+ *** POTENTIAL INCOMPATIBILITY ***</p>
+ <p>
+ Own Id: OTP-8671</p>
+ </item>
+ <item>
+ <p>
+ Alignment of scheduler data and run queues were adjusted.</p>
+ <p>
+ Own Id: OTP-8673</p>
+ </item>
+ <item>
+ <p>Call time breakpoint tracing</p> <list><item>Introduce
+ a <c>call_time</c> option to
+ <c>erlang:trace_pattern/3</c>.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 <c>erlang:trace_info/2</c></item>
+ <item>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.</item></list>
+ <p>Teach call count tracing to use atomics</p>
+ <list><item>Call count previously used a global lock for
+ accessing and writing its counter in the breakpoint. This
+ is now changed to atomics instead.</item> <item>The
+ change will let call count tracing and cprof to scale
+ better when increasing the number of
+ schedulers.</item></list>
+ <p>
+ Own Id: OTP-8677</p>
+ </item>
+ <item>
+ <p><c>eprof</c> 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).</p>
+ <p>Note: The API for the <c>eprof</c> has been cleaned up
+ and extended. See the documentation.</p>
+ <p>
+ *** POTENTIAL INCOMPATIBILITY ***</p>
+ <p>
+ Own Id: OTP-8706</p>
+ </item>
+ </list>
+ </section>
+
+</section>
+
<section><title>Erts 5.7.5</title>
<section><title>Fixed Bugs and Malfunctions</title>