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<p>This document describes the changes made to the ERTS application.</p>
+<section><title>Erts 9.0</title>
+
+ <section><title>Fixed Bugs and Malfunctions</title>
+ <list>
+ <item>
+ <p>Fix various bugs regarding loading, upgrade and purge
+ of HiPE compiled code:</p> <list> <item>The native code
+ memory for a purged module was never deallocated.</item>
+ <item>Wrong functions could in some cases be called after
+ a module upgrade.</item>
+ <item><c>erlang:check_process_code</c> did not check for
+ recursive calls made from native code.</item> </list>
+ <p>
+ Own Id: OTP-13968</p>
+ </item>
+ <item>
+ <p>
+ Hipe optional LLVM backend does require LLVM version 3.9
+ or later as older versions forced strong dependencies on
+ erts internals structures.</p>
+ <p>
+ Own Id: OTP-14238</p>
+ </item>
+ <item>
+ <p>
+ Slogans in crash dumps have been extended to print more
+ complex terms.</p>
+ <p>
+ Own Id: OTP-14303</p>
+ </item>
+ <item>
+ <p>
+ Fixed bug when using <c>enif_inspect_binary</c> in
+ combination with <c>enif_copy</c>. In some circumstances
+ the inspected binary could be realloced by the
+ <c>enif_copy</c> call when it shouldn't have been.</p>
+ <p>
+ Own Id: OTP-14304</p>
+ </item>
+ <item>
+ <p>
+ Use <c>-fno-PIE</c> for Gentoo Hardened and others that
+ don't accept linker flag <c>-no-pie</c>.</p>
+ <p>
+ Own Id: OTP-14307 Aux Id: PR-1379 </p>
+ </item>
+ <item>
+ <p>
+ Disable hipe for <c>ppc64le</c> architecture (little
+ endian) as it is not, and has never been, supported. It
+ was earlier equated with <c>ppc64</c> (big endian) which
+ lead to broken build without <c>--disable-hipe</c>.</p>
+ <p>
+ Own Id: OTP-14314 Aux Id: ERL-369, PR-1394 </p>
+ </item>
+ <item>
+ <p>
+ Fix 'epmd -kill' to return a failure exit status code if
+ epmd was not killed because of some error.</p>
+ <p>
+ Own Id: OTP-14324</p>
+ </item>
+ <item>
+ <p>Fixed the following dirty scheduler related bugs:</p>
+ <list> <item><p>the <c>+SDPcpu</c> command line argument
+ could cause the amount of dirty CPU schedulers to be set
+ to zero</p></item>
+ <item><p><c>erlang:system_flag(multi_scheduling, _)</c>
+ failed when only one normal scheduler was used together
+ with dirty scheduler support</p></item> </list>
+ <p>
+ Own Id: OTP-14335</p>
+ </item>
+ <item>
+ <p>
+ Fix erlexec to handle mismatch in sysconf and proc fs
+ when figuring out the cpu topology. This behaviour has
+ been seen when using docker together with
+ <c>--cpuset-cpus</c>.</p>
+ <p>
+ Own Id: OTP-14352</p>
+ </item>
+ <item>
+ <p>
+ Fixed memory segment cache used for multiblock carriers.
+ Huge (> 2GB) memory segments could cause a VM crash.
+ Creation of such huge memory segments used for multiblock
+ carriers is however very uncommon.</p>
+ <p>
+ Own Id: OTP-14360 Aux Id: ERL-401, PR-1417 </p>
+ </item>
+ </list>
+ </section>
+
+
+ <section><title>Improvements and New Features</title>
+ <list>
+ <item>
+ <p>
+ Added <c>erlang:garbage_collect/2</c> that takes an
+ option list as the last argument that can be used to
+ control whether a minor or a major garbage collection is
+ to be done. Doing a minor collection only collects terms
+ that have recently died, but is cheaper than a mjor
+ collection.</p>
+ <p>
+ Own Id: OTP-11695</p>
+ </item>
+ <item>
+ <p>
+ Optimized test for tuples with an atom as first element.</p>
+ <p>
+ Own Id: OTP-12148</p>
+ </item>
+ <item>
+ <p>
+ Erlang literals are no longer copied during process to
+ process messaging.</p>
+ <p>
+ Own Id: OTP-13529</p>
+ </item>
+ <item>
+ <p>Add support in the <c>erl_nif</c> API for asynchronous
+ message notifications when sockets or other file
+ descriptors are ready to accept read or write operations.
+ The following functions have been added:</p> <list>
+ <item><p>enif_select</p></item>
+ <item><p>enif_monitor_process</p></item>
+ <item><p>enif_demonitor_process</p></item>
+ <item><p>enif_compare_monitors</p></item>
+ <item><p>enif_open_resource_type_x</p></item> </list>
+ <p>
+ Own Id: OTP-13684</p>
+ </item>
+ <item>
+ <p>There are two new guard BIFs '<c>floor/1</c>' and
+ '<c>ceil/1</c>'. They both return integers. In the
+ '<c>math</c>' module, there are two new BIFs with the
+ same names that return floating point values.</p>
+ <p>
+ Own Id: OTP-13692</p>
+ </item>
+ <item>
+ <p>
+ Remove deprecated <c>erlang:hash/2</c>.</p>
+ <p>
+ *** POTENTIAL INCOMPATIBILITY ***</p>
+ <p>
+ Own Id: OTP-13827</p>
+ </item>
+ <item>
+ <p>Replaced usage of deprecated symbolic <seealso
+ marker="erts:erlang#type-time_unit"><c>time
+ unit</c></seealso> representations.</p>
+ <p>
+ Own Id: OTP-13831 Aux Id: OTP-13735 </p>
+ </item>
+ <item>
+ <p>
+ Added support in zlib for extraction of the inflation
+ dictionary.</p>
+ <p>
+ Own Id: OTP-13842</p>
+ </item>
+ <item>
+ <p>
+ The previously used purge strategy has been removed. The
+ optional purge strategy introduced in ERTS version 8.1 is
+ now the only strategy available.</p>
+ <p>
+ The new purge strategy is slightly incompatible with the
+ old strategy. Previously processes holding <c>fun</c>s
+ that referred to the module being purged either failed a
+ soft purge, or was killed during a hard purge. The new
+ strategy completely ignores <c>fun</c>s. If <c>fun</c>s
+ referring to the code being purged exist, and are used
+ after a purge, an exception will be raised upon usage.
+ That is, the behavior will be exactly the same as the
+ case when a <c>fun</c> is received by a process after the
+ purge.</p>
+ <p>
+ For more information see the documentation of <seealso
+ marker="erts:erlang#check_process_code/3"><c>erlang:check_process_code/3</c></seealso>.</p>
+ <p>
+ *** POTENTIAL INCOMPATIBILITY ***</p>
+ <p>
+ Own Id: OTP-13844 Aux Id: OTP-13833 </p>
+ </item>
+ <item>
+ <p>
+ Dirty schedulers are now enabled by default when the
+ runtime system is built with SMP support.</p>
+ <p>
+ Own Id: OTP-13860</p>
+ </item>
+ <item>
+ <p>
+ Improved ETS lookup/insert/delete speed for large
+ <c>set</c>, <c>bag</c> and <c>duplicate_bag</c> by a
+ significant reduction of the hash load factor. This speed
+ improvement comes at the expense of less than one word
+ per table entry. Tables with less than 256 entries are
+ not affected at all.</p>
+ <p>
+ Own Id: OTP-13903</p>
+ </item>
+ <item>
+ <p>
+ The NIF library <c>reload</c> feature is not supported
+ anymore. It has been marked as deprecated since OTP R15B.
+ This means that you are only allowed to do one successful
+ call to <c>erlang:load_nif/2</c> for each module
+ instance. A second call to <c>erlang:load_nif/2</c> will
+ return <c>{error, {reload, _}}</c> even if the NIF
+ library imlements the <c>reload</c> callback.</p>
+ <p>
+ Runtime upgrade of a NIF library is still supported by
+ using the Erlang module upgrade mechanics with a current
+ and an old module instance existing at the same time with
+ their corresponding NIF libraries.</p>
+ <p>
+ *** POTENTIAL INCOMPATIBILITY ***</p>
+ <p>
+ Own Id: OTP-13908</p>
+ </item>
+ <item>
+ <p>
+ Add <c>erlang:system_info(atom_count)</c> and
+ <c>erlang:system_info(atom_limit)</c> to provide a way to
+ retrieve the current and maximum number of atoms.</p>
+ <p>
+ Own Id: OTP-13976</p>
+ </item>
+ <item>
+ <p>The function <c>fmod/2</c> has been added to the
+ <c>math</c> module.</p>
+ <p>
+ Own Id: OTP-14000</p>
+ </item>
+ <item>
+ <p>
+ <c>erlang:load_nif/2</c> returns new error type
+ <c>notsup</c> when called for a HiPE compiled module,
+ which is not supported.</p>
+ <p>
+ Own Id: OTP-14002</p>
+ </item>
+ <item>
+ <p>
+ Add driver and nif lock instrumentation to lcnt</p>
+ <p>
+ Own Id: OTP-14069</p>
+ </item>
+ <item>
+ <p>
+ Reduce memory pressure by converting sub-binaries to
+ heap-binaries when possible. This is done during garbage
+ collection.</p>
+ <p>
+ Own Id: OTP-14149</p>
+ </item>
+ <item>
+ <p>
+ Dirty schedulers are now enabled and supported on Erlang
+ runtime systems with SMP support.</p>
+ <p>
+ Besides support for dirty NIFs also support for dirty
+ BIFs and dirty garbage collection have been introduced.
+ All garbage collections that potentially will take a long
+ time to complete are now performed on dirty schedulers if
+ enabled.</p>
+ <p>
+ <seealso
+ marker="erts:erlang#statistics_scheduler_wall_time"><c>erlang:statistics(scheduler_wall_time)</c></seealso>
+ now also includes information about dirty CPU schedulers.
+ Code using <c>erlang:statistics(scheduler_wall_time)</c>
+ may have to be rewritten to take this incompatibility
+ into consideration.</p>
+ <p>
+ *** POTENTIAL INCOMPATIBILITY ***</p>
+ <p>
+ Own Id: OTP-14152</p>
+ </item>
+ <item>
+ <p>Atoms may now contain arbitrary Unicode
+ characters.</p>
+ <p>
+ Own Id: OTP-14178</p>
+ </item>
+ <item>
+ <p>
+ Introduce an event manager in Erlang to handle OS
+ signals. A subset of OS signals may be subscribed to and
+ those are described in the Kernel application.</p>
+ <p>
+ Own Id: OTP-14186</p>
+ </item>
+ <item>
+ <p>
+ The <c>escript</c> program now handles symbolic links to
+ escripts.</p>
+ <p>
+ This is useful for standalone systems with
+ <c>escript</c>s residing on a bin directory not included
+ in the execution path (as it may cause their <c>erl</c>
+ program(s) to override the desired one). Instead the
+ <c>escript</c>s can be referred to via symbolic links
+ from a bin directory in the path.</p>
+ <p>
+ Own Id: OTP-14201 Aux Id: PR-1293 </p>
+ </item>
+ <item>
+ <p>
+ All uses of the magic binary kludge has been replaced by
+ uses of erlang references.</p>
+ <p>
+ A magic binary was presented as an empty binary, but
+ actually referred other data internally in the Erlang VM.
+ Since they were presented as empty binaries, different
+ magic binaries compared as equal, and also lost their
+ internal data when passed out of an erlang node.</p>
+ <p>
+ The new usage of references has not got any of these
+ strange semantic issues, and the usage of these
+ references has been optimized to give the same
+ performance benefits as well as memory usage benefits as
+ magic binaries had.</p>
+ <p>
+ A couple of examples of previous uses of magic binaries
+ are match specifications and NIF resources.</p>
+ <p>
+ Own Id: OTP-14205</p>
+ </item>
+ <item>
+ <p>
+ The non-smp emulators have been deprecated and are
+ scheduled for removal in OTP-21.</p>
+ <p>
+ In preperations for this, the threaded non-smp emulator
+ is no longer built by default and has to be enabled using
+ the --enable-plain-emulator to configure.</p>
+ <p>
+ *** POTENTIAL INCOMPATIBILITY ***</p>
+ <p>
+ Own Id: OTP-14272</p>
+ </item>
+ <item>
+ <p>
+ Allow HiPE to run on VM built with
+ <c>--enable-m32-build</c>.</p>
+ <p>
+ Own Id: OTP-14330 Aux Id: PR-1397 </p>
+ </item>
+ <item>
+ <p>
+ Upgraded the OTP internal PCRE library from version 8.33
+ to version 8.40. This library is used for implementation
+ of the <seealso marker="stdlib:re"><c>re</c></seealso>
+ regular expressions module.</p>
+ <p>
+ Besides various bug fixes, the new version allows for
+ better stack protection. In order to utilize this
+ feature, the stack size of normal scheduler threads is
+ now by default set to 128 kilo words on all platforms.
+ The stack size of normal scheduler threads can be set
+ upon system start by passing the <seealso
+ marker="erts:erl#sched_thread_stack_size"><c>+sss</c></seealso>
+ command line argument to the <seealso
+ marker="erts:erl"><c>erl</c></seealso> command.</p>
+ <p>
+ See <url
+ href="http://pcre.org/original/changelog.txt"><c>http://pcre.org/original/changelog.txt</c></url>
+ for information about changes made to PCRE between the
+ versions 8.33 and 8.40.</p>
+ <p>
+ *** POTENTIAL INCOMPATIBILITY ***</p>
+ <p>
+ Own Id: OTP-14331 Aux Id: ERL-208 </p>
+ </item>
+ <item>
+ <p>
+ Remove generation of atoms in old latin1 external format.
+ The old latin1 format can still be decoded but is never
+ generated by <c>term_to_binary</c> or sent on a
+ distribution channel. The new utf8 format for atoms was
+ introduced in OTP R16. An OTP 20 node can therefore not
+ connect to nodes older than R16.</p>
+ <p>
+ Own Id: OTP-14337</p>
+ </item>
+ <item>
+ <p>
+ Added function <c>re:version/0</c> which returns
+ information about the OTP internal PCRE version used for
+ implementation of the <c>re</c> module.</p>
+ <p>
+ Own Id: OTP-14347 Aux Id: PR-1412 </p>
+ </item>
+ <item>
+ <p>
+ Added new debug bif <c>erlang:list_to_port/1</c>.</p>
+ <p>
+ Own Id: OTP-14348</p>
+ </item>
+ <item>
+ <p>
+ Various improvements of timer management internally in
+ the VM. These improvements both reduced memory
+ consumption of timer wheels as well as reduce the amount
+ of work that has to be performed in order to handle
+ timers.</p>
+ <p>
+ Own Id: OTP-14356</p>
+ </item>
+ <item>
+ <p> Sockets can now be bound to device (SO_BINDTODEVICE)
+ on platforms where it is supported. </p> <p> This has
+ been implemented e.g to support VRF-Lite under Linux; see
+ <url
+ href="https://www.kernel.org/doc/Documentation/networking/vrf.txt">
+ VRF </url>, and GitHub pull request <url
+ href="https://github.com/erlang/otp/pull/1326">#1326</url>.
+ </p>
+ <p>
+ Own Id: OTP-14357 Aux Id: PR-1326 </p>
+ </item>
+ <item>
+ <p>Added the following <seealso
+ marker="erl"><c>erl</c></seealso> command line arguments
+ with which you can set suggested stack for dirty
+ schedulers:</p> <taglist> <tag><seealso
+ marker="erl#dcpu_sched_thread_stack_size"><c>+sssdcpu</c></seealso></tag>
+ <item><p>for dirty CPU schedulers</p></item>
+ <tag><seealso
+ marker="erl#dio_sched_thread_stack_size"><c>+sssdio</c></seealso></tag>
+ <item><p>for dirty IO schedulers</p></item> </taglist>
+ <p>The default suggested stack size for dirty schedulers
+ is 40 kilo words.</p>
+ <p>
+ Own Id: OTP-14380</p>
+ </item>
+ <item>
+ <p>
+ Changed erts startup program name, argv 0, to use the
+ environment variable <c>ESCRIPT_NAME</c> so that
+ <c>erlc</c>, <c>dialyzer</c>, <c>typer</c>,
+ <c>ct_run</c>, or the escript name can be seen with
+ external programs, such as ps and htop (depending on
+ options), on unix.</p>
+ <p>
+ If environment variable <c>ESCRIPT_NAME</c> is not set,
+ argv 0 of the invoking program will be used, e.g. the
+ name will be <c>erl</c>, <c>cerl</c>, or the soft link
+ name.</p>
+ <p>
+ Own Id: OTP-14381</p>
+ </item>
+ <item>
+ <p>
+ Improvements of <c>escript</c> documentation.</p>
+ <p>
+ Own Id: OTP-14384 Aux Id: OTP-14201 </p>
+ </item>
+ <item>
+ <p>
+ Add function <c>enif_hash</c> for NIFs to calculate hash
+ values of arbitrary terms.</p>
+ <p>
+ Own Id: OTP-14385 Aux Id: PR-1413 </p>
+ </item>
+ </list>
+ </section>
+
+</section>
+
<section><title>Erts 8.3.3</title>
<section><title>Fixed Bugs and Malfunctions</title>