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authorErlang/OTP <[email protected]>2018-05-25 12:14:27 +0200
committerErlang/OTP <[email protected]>2018-05-25 12:14:27 +0200
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</header>
<p>This document describes the changes made to the ERTS application.</p>
+<section><title>Erts 10.0</title>
+
+ <section><title>Fixed Bugs and Malfunctions</title>
+ <list>
+ <item>
+ <p>
+ The type specifications for <c>file:posix/0</c> and
+ <c>inet:posix/0</c> have been updated according to which
+ errors file and socket operations should be able to
+ return.</p>
+ <p>
+ Own Id: OTP-14019 Aux Id: ERL-550 </p>
+ </item>
+ <item>
+ <p>
+ Fix error printout from run_erl and a bug that could
+ cause unintended fds to be leaked into the started
+ program.</p>
+ <p>
+ Own Id: OTP-14537 Aux Id: PR1529 </p>
+ </item>
+ <item>
+ <p> File operations used to accept <seealso
+ marker="kernel:file#type-name_all">filenames</seealso>
+ containing null characters (integer value zero). This
+ caused the name to be truncated and in some cases
+ arguments to primitive operations to be mixed up.
+ Filenames containing null characters inside the filename
+ are now <em>rejected</em> and will cause primitive file
+ operations to fail. </p> <p> Also environment variable
+ operations used to accept <seealso
+ marker="kernel:os#type-env_var_name">names</seealso> and
+ <seealso
+ marker="kernel:os#type-env_var_value">values</seealso> of
+ environment variables containing null characters (integer
+ value zero). This caused operations to silently produce
+ erroneous results. Environment variable names and values
+ containing null characters inside the name or value are
+ now <em>rejected</em> and will cause environment variable
+ operations to fail. </p> <p>Primitive environment
+ variable operations also used to accept the <c>$=</c>
+ character in environment variable names causing various
+ problems. <c>$=</c> characters in environment variable
+ names are now also <em>rejected</em>. </p> <p>Also
+ <seealso
+ marker="kernel:os#cmd/1"><c>os:cmd/1</c></seealso> now
+ reject null characters inside its <seealso
+ marker="kernel:os#type-os_command">command</seealso>.
+ </p> <p><seealso
+ marker="erts:erlang#open_port/2"><c>erlang:open_port/2</c></seealso>
+ will also reject null characters inside the port name
+ from now on.</p>
+ <p>
+ *** POTENTIAL INCOMPATIBILITY ***</p>
+ <p>
+ Own Id: OTP-14543 Aux Id: ERL-370 </p>
+ </item>
+ <item>
+ <p>
+ Fix bugs related to the bookkeeping of microstate
+ accounting states.</p>
+ <p>
+ Own Id: OTP-14652</p>
+ </item>
+ <item>
+ <p><c>os:putenv</c> and <c>os:getenv</c> no longer access
+ the process environment directly and instead work on a
+ thread-safe emulation. The only observable difference is
+ that it's <em>not</em> kept in sync with libc
+ <c>getenv(3)</c> / <c>putenv(3)</c>, so those who relied
+ on that behavior in drivers or NIFs will need to add
+ manual synchronization.</p> <p>On Windows this means that
+ you can no longer resolve DLL dependencies by modifying
+ the <c>PATH</c> just before loading the driver/NIF. To
+ make this less of a problem, the emulator now adds the
+ target DLL's folder to the DLL search path.</p>
+ <p>
+ *** POTENTIAL INCOMPATIBILITY ***</p>
+ <p>
+ Own Id: OTP-14666</p>
+ </item>
+ <item>
+ <p>Corrected <c>erlang:is_builtin(erlang, M, F)</c> to
+ return <c>true</c> for <c>apply/2</c> and
+ <c>yield/0</c>.</p>
+ <p>
+ Own Id: OTP-14713 Aux Id: ERL-500 </p>
+ </item>
+ <item>
+ <p>Fixed a bug where the PATH environment variable wasn't
+ updated correctly on a release downgrade, effectively
+ keeping the PATH of the new release.</p>
+ <p>
+ Own Id: OTP-14719</p>
+ </item>
+ <item>
+ <p>A receive optimization that avoids scanning the entire
+ message queue when receiving a message containing a
+ freshly created reference could in rare circumstances
+ (involving recursive calls to the functions that does the
+ receive) cause the receive to hang. This has been
+ corrected.</p>
+ <p>
+ Own Id: OTP-14782 Aux Id: ERL-511 </p>
+ </item>
+ <item>
+ <p>
+ Fix building of Erlang/OTP on platforms which have small
+ data area with short addressing. For example the
+ PowerPC/RTEMS platform.</p>
+ <p>
+ Own Id: OTP-14909 Aux Id: PR-1692 </p>
+ </item>
+ <item>
+ <p>Fixed a crash when <c>enif_make_binary</c> is called
+ with a binary produced by <c>enif_inspect_binary</c> in a
+ different environment.</p>
+ <p>
+ Own Id: OTP-14931</p>
+ </item>
+ <item>
+ <p>Fixed a crash when <c>enif_make_binary</c> is called
+ more than once with a binary that had previously been
+ added to an <c>enif_ioq</c>.</p>
+ <p>
+ Own Id: OTP-14932</p>
+ </item>
+ <item>
+ <p>
+ The erl_child_setup program now ignores SIGTERM signals.</p>
+ <p>
+ Own Id: OTP-14943 Aux Id: ERL-576 </p>
+ </item>
+ <item>
+ <p>
+ Force 64-bit alignment on pre-allocators on architectures
+ which needs it.</p>
+ <p>
+ Own Id: OTP-14977</p>
+ </item>
+ <item>
+ <p>
+ Fixed a bug where dirty scheduler picked up non-dirty
+ work.</p>
+ <p>
+ Own Id: OTP-14978</p>
+ </item>
+ <item>
+ <p>
+ Calls to <c>gen_tcp:send/2</c> on closed sockets now
+ returns <c>{error, closed}</c> instead of
+ <c>{error,enotconn}</c>.</p>
+ <p>
+ Own Id: OTP-15001</p>
+ </item>
+ <item>
+ <p>
+ <c>erlang:monotonic_time/1</c> failed with <c>badarg</c>
+ when passing the <c>perf_counter</c> time unit as
+ argument.</p>
+ <p>
+ Own Id: OTP-15008</p>
+ </item>
+ <item>
+ <p>
+ Fix bug where rapid <c>init:restart()</c> calls would
+ sometimes crash because a code load request leaked in
+ between the restarts.</p>
+ <p>
+ Own Id: OTP-15013</p>
+ </item>
+ <item>
+ <p>
+ Improve <c>float_to_list(F, [{decimals,D}])</c> to closer
+ conform with <c>io_lib:format("~.*f", [D,F])</c>.</p>
+ <p>
+ There are however, still cases when <c>float_to_list</c>
+ does not produce the exact same result as
+ <c>io_lib:format</c>, especially for large values
+ <c>F</c> and/or many decimals <c>D</c>.</p>
+ <p>
+ Own Id: OTP-15015 Aux Id: OTP-14890 </p>
+ </item>
+ <item>
+ <p>Fixed a deadlock that would occur on certain
+ allocators when a reallocation failed with <c>+ramv</c>
+ enabled.</p>
+ <p>
+ Own Id: OTP-15024</p>
+ </item>
+ <item>
+ <p>
+ Fix bug that made it impossible to use an erl_tracer as
+ the seq_trace trace receiver.</p>
+ <p>
+ Own Id: OTP-15029</p>
+ </item>
+ <item>
+ <p>
+ Fix bug where a large (> 1 GB) emulator generated error
+ logger message would cause the emulator to crash.</p>
+ <p>
+ Own Id: OTP-15032</p>
+ </item>
+ <item>
+ <p>The emulator will no longer crash when reading the
+ file information of an ordinary file that has an NTFS
+ reparse point, such as files stored in a OneDrive-mapped
+ folder.</p>
+ <p>
+ Own Id: OTP-15062 Aux Id: ERL-615 </p>
+ </item>
+ <item>
+ <p>
+ Fixed bug in <c>enif_binary_to_term</c> which could cause
+ memory corruption for immediate terms (atoms, small
+ integers, pids, ports, empty lists).</p>
+ <p>
+ Own Id: OTP-15080</p>
+ </item>
+ <item>
+ <p>
+ Fixed bug in <c>erlang:system_profile/2</c> that could
+ cause superfluous <c>{profile,_,active,_,_}</c> messages
+ for terminating processes.</p>
+ <p>
+ Own Id: OTP-15085</p>
+ </item>
+ <item>
+ <p>
+ On OSs with per thread CPU time support, change
+ <c>cpu_timestamp</c> in <seealso
+ marker="erlang#trace/3">erlang:trace/3</seealso> to use
+ it instead of per process CPU time. This makes this
+ option useable on such OSs when running multiple
+ schedulers.</p>
+ <p>
+ Own Id: OTP-15090</p>
+ </item>
+ </list>
+ </section>
+
+
+ <section><title>Improvements and New Features</title>
+ <list>
+ <item>
+ <p>It is now possible to open device files and FIFOs with
+ <c>file:open/2</c>.</p>
+ <p>
+ Own Id: OTP-11462</p>
+ </item>
+ <item>
+ <p>
+ The <c>erlang:system_flag(scheduler_wall_time,Bool)</c>
+ call is now reference counted and will be turned off if
+ the (last) process that started the performance
+ statistics dies. Thus it is no longer possible to start
+ the statistics with <c>rpc:call(Node, erlang,
+ system_flag, [scheduler_wall_time, true])</c> since it
+ will be turned off directly afterwards when the rpc
+ process dies.</p>
+ <p>
+ *** POTENTIAL INCOMPATIBILITY ***</p>
+ <p>
+ Own Id: OTP-11694</p>
+ </item>
+ <item>
+ <p>A new logging API is added to Erlang/OTP, see the
+ <seealso
+ marker="kernel:logger"><c>logger(3)</c></seealso> manual
+ page, and section <seealso
+ marker="kernel:logger_chapter">Logging</seealso> in the
+ Kernel User's Guide.</p>
+ <p>Calls to <c>error_logger</c> are automatically
+ redirected to the new API, and legacy error logger event
+ handlers can still be used. It is, however, recommended
+ to use the Logger API directly when writing new code.</p>
+ <p>Notice the following potential incompatibilities:</p>
+ <list> <item><p>Kernel configuration parameters
+ <c>error_logger</c> still works, but is overruled if the
+ default handler's output destination is configured with
+ Kernel configuration parameter <c>logger</c>.</p> <p>In
+ general, parameters for configuring error logger are
+ overwritten by new parameters for configuring
+ Logger.</p></item> <item><p>The concept of SASL error
+ logging is deprecated, meaning that by default the SASL
+ application does not affect which log events are
+ logged.</p> <p>By default, supervisor reports and crash
+ reports are logged by the default Logger handler started
+ by Kernel, and end up at the same destination (terminal
+ or file) as other standard log event from Erlang/OTP.</p>
+ <p>Progress reports are not logged by default, but can be
+ enabled with the Kernel configuration parameter
+ <c>logger_progress_reports</c>.</p> <p>To obtain
+ backwards compatibility with the SASL error logging
+ functionality from earlier releases, set Kernel
+ configuration parameter <c>logger_sasl_compatible</c> to
+ <c>true</c>. This prevents the default Logger handler
+ from logging any supervisor-, crash-, or progress
+ reports. Instead, SASL adds a separate Logger handler
+ during application start, which takes care of these log
+ events. The SASL configuration parameters
+ <c>sasl_error_logger</c> and <c>sasl_errlog_type</c>
+ specify the destination (terminal or file) and severity
+ level to log for these events.</p></item></list>
+ <p>
+ *** POTENTIAL INCOMPATIBILITY ***</p>
+ <p>
+ Own Id: OTP-13295</p>
+ </item>
+ <item>
+ <p>
+ <c>gen_sctp:connect_init/4</c> or rather connect in
+ <c>inet_drv.c</c> for SCTP has been fixed to not check
+ the write file descriptor for writeability after a
+ connect, since for SCTP (SOCK_SEQPACKET) that property
+ does not seem to be any kind of indicator for when a
+ connect has finished. This fixes connects that the OS
+ returned as "in progress" that was misinterpreted by
+ <c>gen_sctp:connect_init</c> as failed.</p>
+ <p>
+ Own Id: OTP-13760 Aux Id: PR-1592 </p>
+ </item>
+ <item>
+ <p>The file driver has been rewritten as a NIF,
+ decreasing the latency of file operations. Two notable
+ incompatibilities are:</p> <list> <item><p>The
+ <c>use_threads</c> option for <c>file:sendfile/5</c> no
+ longer has any effect; we either use non-blocking
+ <c>sendfile(2)</c> or fall back to <c>file:read</c> +
+ <c>gen_tcp:send</c>. </p></item> <item><p>The
+ file-specific DTrace probes have been removed. The same
+ effect can be achieved with normal tracing together with
+ the <c>nif__entry</c>/<c>nif__return</c> probes to track
+ scheduling.</p></item> </list>
+ <p>
+ *** POTENTIAL INCOMPATIBILITY ***</p>
+ <p>
+ Own Id: OTP-14256</p>
+ </item>
+ <item>
+ <p>The I/O polling functionality of erts has been
+ re-written to better make use of the OSs polling
+ mechanisms. This change means that erts will now always
+ prefer to use a kernel-polling mechanism if possible.
+ Also all of the I/O polling has been moved to dedicated
+ threads instead of being placed in the scheduler
+ loops.</p> <p>As a result of this, the <c>erl</c> options
+ <c>+K</c> and <c>+secio</c> have been removed. It is
+ still possible to disable kernel-poll, but it has to be
+ done at compile time through the configure option
+ <c>--disable-kernel-poll</c>.</p> <p>The new <c>erl</c>
+ options <seealso marker="erl#+IOt"><c>+IOt</c></seealso>
+ and <seealso marker="erl#+IOp"><c>+IOp</c></seealso> can
+ be used to change how many IO poll threads and poll sets
+ that erts should use. See their respective documentation
+ for more details.</p>
+ <p>
+ Own Id: OTP-14346</p>
+ </item>
+ <item>
+ <p>Truly asynchronous auto-connect. Earlier, when
+ <c>erlang:send</c> was done toward an unconnected node,
+ the function would not return until the connection setup
+ had completed (or failed). Now the function returns
+ directly after the signal has been enqueued and the
+ connection setup started.</p>
+ <p>The same applies to all distributed operations that
+ may trigger auto-connect, i.e. <c>'!'</c>, <c>send</c>,
+ <c>link</c>, <c>monitor</c>, <c>monitor_node</c>,
+ <c>exit/2</c> and <c>group_leader</c>.</p>
+ <p>The interface for all these functions are unchanged as
+ they do not return connection failures. The only
+ exception is <c>erlang:monitor</c> where a <em>possible
+ incompatibility</em> is introduced: An attempt to monitor
+ a process on a primitive node (such as erl_interface or
+ jinterface), where remote process monitoring is not
+ implemented, will no longer fail with <c>badarg</c>
+ exception. Instead a monitor will be created, but it will
+ only supervise the connection to the node.</p>
+ <p>
+ *** POTENTIAL INCOMPATIBILITY ***</p>
+ <p>
+ Own Id: OTP-14370</p>
+ </item>
+ <item>
+ <p>Changed the default behaviour of <c>.erlang</c>
+ loading: <c>.erlang</c> is no longer loaded from the
+ current directory. <c>c:erlangrc(PathList)</c> can be
+ used to search and load an <c>.erlang</c> file from user
+ specified directories.</p> <p><c>escript</c>,
+ <c>erlc</c>, <c>dialyzer</c> and <c>typer</c> no longer
+ load an <c>.erlang</c> at all.</p>
+ <p>
+ *** POTENTIAL INCOMPATIBILITY ***</p>
+ <p>
+ Own Id: OTP-14439</p>
+ </item>
+ <item>
+ <p>
+ New functionality for implementation of alternative
+ carriers for the Erlang distribution has been introduced.
+ This mainly consists of support for usage of distribution
+ controller processes (previously only ports could be used
+ as distribution controllers). For more information see
+ <seealso marker="erts:alt_dist#distribution_module">ERTS
+ User's Guide ➜ How to implement an Alternative Carrier
+ for the Erlang Distribution ➜ Distribution
+ Module</seealso>.</p>
+ <p>
+ Own Id: OTP-14459</p>
+ </item>
+ <item>
+ <p>
+ Add support for the lcc compiler and in extension the
+ Elbrus 2000 platform.</p>
+ <p>
+ Own Id: OTP-14492</p>
+ </item>
+ <item>
+ <p>Support for "tuple calls" have been removed from the
+ run-time system. Tuple calls was an undocumented and
+ unsupported feature which allowed the module argument for
+ an apply operation to be a tuple: <c>Var = dict:new(),
+ Var:size()</c>. This "feature" frequently caused
+ confusion, especially when such call failed. The
+ stacktrace would point out functions that don't exist in
+ the source code.</p>
+ <p>For legacy code that need to use parameterized modules
+ or tuple calls for some other reason, there is a new
+ compiler option called <c>tuple_calls</c>. When this
+ option is given, the compiler will generate extra code
+ that emulates the old behavior for calls where the module
+ is a variable.</p>
+ <p>
+ *** POTENTIAL INCOMPATIBILITY ***</p>
+ <p>
+ Own Id: OTP-14497</p>
+ </item>
+ <item>
+ <p>Creation of small maps with literal keys has been
+ optimized to be faster and potentially use less memory.
+ The keys are combined into a literal key tuple which is
+ put into the literal pool. The key tuple can be shared
+ between many instances of maps having the same keys.</p>
+ <p>
+ Own Id: OTP-14502</p>
+ </item>
+ <item>
+ <p>
+ When an exception is thrown, include the arguments of the
+ call in the stacktrace for BIFs <c>band</c>, <c>bor</c>,
+ <c>bsl</c>, <c>bsr</c>, <c>bxor</c>, <c>div</c>,
+ <c>rem</c> and the operators <c>+</c>, <c>-</c>, <c>*</c>
+ and <c>/</c>.</p>
+ <p>
+ *** POTENTIAL INCOMPATIBILITY ***</p>
+ <p>
+ Own Id: OTP-14508</p>
+ </item>
+ <item>
+ <p>
+ The non-smp emulators have been removed. This means that
+ the configure options <c>--disable-threads</c> and
+ <c>--enable-plain-emulator</c> have been removed and
+ configure will now refuse to build Erlang/OTP on
+ platforms without thread support.</p>
+ <p>
+ In order to achieve a similar setup as the non-smp
+ emulator, it is possible to start Erlang/OTP with the
+ <c>+S 1</c> option.</p>
+ <p>
+ *** POTENTIAL INCOMPATIBILITY ***</p>
+ <p>
+ Own Id: OTP-14518</p>
+ </item>
+ <item>
+ <p>Modules that use floating point constants compiled
+ with R15 or earlier will need to be re-compiled before
+ they can be loaded.</p>
+ <p>
+ Own Id: OTP-14575</p>
+ </item>
+ <item>
+ <p>
+ Implementation of true asynchronous signaling between
+ processes in order to improve scalability. Signals
+ affected include exit, monitor, demonitor, monitor
+ triggered, link, unlink, and group leader.</p>
+ <p>
+ Own Id: OTP-14589</p>
+ </item>
+ <item>
+ <p>
+ Added a PGO (profile guided optimization) pass to the
+ build step of erts. This can be disabled by passing
+ --disable-pgo to configure.</p>
+ <p>
+ Own Id: OTP-14604</p>
+ </item>
+ <item>
+ <p>
+ Improved the performance of <c>binary:split</c> and
+ <c>binary:match</c>.</p>
+ <p>
+ Own Id: OTP-14610 Aux Id: PR-1480 </p>
+ </item>
+ <item>
+ <p>
+ It is not longer possible to disable dirty schedulers
+ when building erlang.</p>
+ <p>
+ Own Id: OTP-14613</p>
+ </item>
+ <item>
+ <p>Loaded BEAM code in a 64-bit system requires less
+ memory because of better packing of operands for
+ instructions.</p>
+ <p>These memory savings were achieved by major
+ improvements to the <c>beam_makeops</c> scripts used when
+ building the run time system and BEAM compiler. There is
+ also new for documentation for <c>beam_makeops</c> that
+ describes how new BEAM instructions and loader
+ transformations can be implemented. The documentation is
+ found in here in a source directory or git repository:
+ erts/emulator/internal_doc/beam_makeops.md. An online
+ version can be found here:
+ https://github.com/erlang/otp/blob/master/erts/emulator/internal_doc/beam_makeops.md</p>
+ <p>
+ Own Id: OTP-14626</p>
+ </item>
+ <item>
+ <p><c>file:read_file</c> has been changed to read the
+ content of files that report a size of 0 even when data
+ can be read from them. An example of such a file is
+ <c>/proc/cpuinfo</c> on Linux.</p>
+ <p>
+ Own Id: OTP-14637 Aux Id: ERL-327 PR-1524 </p>
+ </item>
+ <item>
+ <p>
+ It is no longer possible to disable the <c>temp_alloc</c>
+ allocator. Disabling it caused serious performance
+ degradations and was never what was wanted.</p>
+ <p>
+ Own Id: OTP-14651</p>
+ </item>
+ <item>
+ <p>The reduction cost of sending messages is now
+ constant. It will no longer scale according to the length
+ of the receiving process' message queue.</p>
+ <p>
+ Own Id: OTP-14667</p>
+ </item>
+ <item>
+ <p>
+ Improved loading of modules with <c>-on_load</c>
+ directive, to no longer block all schedulers when the
+ load operation is completed.</p>
+ <p>
+ Own Id: OTP-14680</p>
+ </item>
+ <item>
+ <p>
+ On platforms with real-time signals available, SIGRTMIN+1
+ is now used as the internal scheduler suspend signal
+ instead of SIGUSR2.</p>
+ <p>
+ Own Id: OTP-14682</p>
+ </item>
+ <item>
+ <p>When the value returned from a '<c>catch</c>'
+ expression is ignored, no stacktrace will be built if an
+ exception is caught. That will save time and produce less
+ garbage. There are also some minor optimizations of
+ '<c>try</c>/<c>catch</c>' both in the compiler and
+ run-time system.</p>
+ <p>
+ Own Id: OTP-14683</p>
+ </item>
+ <item>
+ <p>The guarantees and non-guarantees of
+ <c>erlang:get_stacktrace/0</c> are now documented.</p>
+ <p>
+ Own Id: OTP-14687</p>
+ </item>
+ <item>
+ <p>There is a new syntax in '<c>try/catch</c>' for
+ retrieving the stacktrace without calling
+ '<c>erlang:get_stacktrace/0</c>'. See the reference
+ manual for a description of the new syntax. The
+ '<c>erlang:get_stacktrace/0</c>' BIF is now
+ deprecated.</p>
+ <p>
+ Own Id: OTP-14692</p>
+ </item>
+ <item>
+ <p>
+ New 'used' option for <c>binary_to_term/2</c> that will
+ also return number of bytes actually read from the
+ binary. This enables easy access to any extra data in the
+ binary located directly after the returned term.</p>
+ <p>
+ Own Id: OTP-14780</p>
+ </item>
+ <item>
+ <p>
+ Added more statistics for
+ <c>erlang:system_info({allocator,A})</c> in the
+ <c>mbcs_pool</c> section.</p>
+ <p>
+ Own Id: OTP-14795 Aux Id: ERL-88 </p>
+ </item>
+ <item>
+ <p>Added <c>enif_ioq_peek_head</c> to retrieve Erlang
+ terms from NIF IO queues without having to resort to
+ copying.</p>
+ <p>
+ Own Id: OTP-14797</p>
+ </item>
+ <item>
+ <p>There is a new option '<c>makedep_side_effect</c>' for
+ the compiler and <c>-MMD</c> for '<c>erlc</c>' that
+ generates dependencies and continues to compile as
+ normal.</p>
+ <p>
+ Own Id: OTP-14830</p>
+ </item>
+ <item>
+ <p>Added <c>ets:whereis/1</c> for retrieving the table
+ identifier of a named table.</p>
+ <p>
+ Own Id: OTP-14884</p>
+ </item>
+ <item>
+ <p><c>seq_trace</c> labels may now be any erlang
+ term.</p>
+ <p>
+ Own Id: OTP-14899</p>
+ </item>
+ <item>
+ <p>
+ Optimized the common case of <c>monitor</c> followed by
+ <c>send</c> to the same local process. The monitor signal
+ is now delayed in order to be piggybacked with the sent
+ message and thereby only get one lock operation on the
+ message queue of the receiver. A delayed monitor signal
+ is flushed if no <c>send</c> has been done at the latest
+ when the process is scheduled out.</p>
+ <p>
+ Own Id: OTP-14901</p>
+ </item>
+ <item>
+ <p>
+ Make hipe compiled code work on x86_64 (amd64) with OS
+ security feature PIE, where executable code can be loaded
+ into a random location. Old behavior, if hipe was
+ enabled, was to disable PIE build options for the VM.</p>
+ <p>
+ Own Id: OTP-14903</p>
+ </item>
+ <item>
+ <p>The number of driver async threads will now default to
+ 1 as the standard drivers do not use them anymore. Users
+ that changed this value to tweak the file driver should
+ replace <c>+A</c> with <c>+SDio</c> since it now uses
+ dirty IO schedulers instead of async threads.</p>
+ <p>
+ *** POTENTIAL INCOMPATIBILITY ***</p>
+ <p>
+ Own Id: OTP-14928</p>
+ </item>
+ <item>
+ <p>
+ Optimize <c>==</c> and <c>/=</c> for binaries with
+ different sizes to be constant in time instead of
+ proportional to the size of their common prefix.</p>
+ <p>
+ Own Id: OTP-14934 Aux Id: PR-1708 </p>
+ </item>
+ <item>
+ <p>
+ Refactorings making some internal process flags available
+ for other usage.</p>
+ <p>
+ Own Id: OTP-14948</p>
+ </item>
+ <item>
+ <p>
+ Removed need for HiPE to allocate native executable
+ memory in low 2GB address space on x86_64. Command line
+ option <c>+MXscs</c> is thereby obsolete and ignored.</p>
+ <p>
+ Own Id: OTP-14951</p>
+ </item>
+ <item>
+ <p>Added <c>enif_make_map_from_arrays</c> for creating a
+ populated map, analogous to
+ <c>enif_make_list_from_array</c>.</p>
+ <p>
+ Own Id: OTP-14954</p>
+ </item>
+ <item>
+ <p>Added configuration switches for busy-wait and wake up
+ thresholds for dirty schedulers, and changing these
+ settings for normal schedulers will no longer affect
+ dirty schedulers. </p> <p>Refer to the documentation for
+ details. The new switches are <seealso
+ marker="erl#+sbwtdcpu">+sbwtdcpu</seealso>, <seealso
+ marker="erl#+sbwtdio">+sbwtdio</seealso>, <seealso
+ marker="erl#+swtdcpu">+swtdcpu</seealso>, and <seealso
+ marker="erl#+swtdio">+swtdio</seealso>.</p> <p>The
+ default busy wait threshold for dirty scheduler threads
+ has also been lowered to <c>short</c>.</p>
+ <p>
+ Own Id: OTP-14959</p>
+ </item>
+ <item>
+ <p>
+ The list of "taints" now also includes dynamic loaded
+ drivers in addition to NIF libraries. Statically linked
+ drivers and NIF libraries that are part of erts are not
+ included. The "taints" are returned by
+ <c>system_info(taints)</c> and printed in the header of
+ <c>erl_crash.dump</c> files.</p>
+ <p>
+ Own Id: OTP-14960</p>
+ </item>
+ <item>
+ <p>Added <c>instrument:allocations</c> and
+ <c>instrument:carriers</c> for retrieving information
+ about memory utilization and fragmentation.</p>
+ <p>The old <c>instrument</c> interface has been removed,
+ as have the related options <c>+Mim</c> and
+ <c>+Mis</c>.</p>
+ <p>
+ *** POTENTIAL INCOMPATIBILITY ***</p>
+ <p>
+ Own Id: OTP-14961</p>
+ </item>
+ <item>
+ <p>The process suspend functionality used by the <seealso
+ marker="erlang:suspend_process/2">erlang:suspend_process/2</seealso>
+ BIF has been reimplemented using the newly introduced
+ true asynchronous signaling between processes. This
+ mainly to reduce memory usage in the process control
+ block of all processes, but also in order to simplify the
+ implementation.</p> <warning> <p>You can easily create
+ deadlocks if processes suspends each other (directly or
+ in circles). In ERTS versions prior to ERTS version 10.0,
+ the runtime system prevented such deadlocks, but this
+ prevention has now been removed due to performance
+ reasons.</p> </warning> <p>Other ERTS internal
+ functionality that used the previous process suspend
+ functionality have also been reimplemented to use
+ asynchronous signaling instead.</p>
+ <p>
+ *** POTENTIAL INCOMPATIBILITY ***</p>
+ <p>
+ Own Id: OTP-14964 Aux Id: OTP-14589 </p>
+ </item>
+ <item>
+ <p>Added the <c>nifs</c> option to
+ <c>?MODULE:module_info/1</c> for listing a module's
+ installed NIF functions.</p>
+ <p>
+ Own Id: OTP-14965</p>
+ </item>
+ <item>
+ <p>
+ New implementation of <c>erlang:process_info/[1,2]</c>.</p>
+ <p>
+ In the general case when inspecting another process, the
+ new implementation sends an asynchronous process-info
+ request signal to the other process and waits for the
+ result instead of locking the other process and reading
+ the result directly. In some special cases where no
+ conflicts occur, signal order wont be violated, and the
+ amount of data requested is guaranteed to be small, the
+ inspected process may be inspected directly.</p>
+ <p>
+ Appropriate amount of reductions are now also bumped when
+ inspecting a process.</p>
+ <p>
+ Own Id: OTP-14966</p>
+ </item>
+ <item>
+ <p>
+ Removed process start time from crash dump in order to
+ save memory in process control block.</p>
+ <p>
+ Own Id: OTP-14975 Aux Id: PR-1597 </p>
+ </item>
+ <item>
+ <p>
+ Optimize <c>erlang:put/2</c> when updating existing key
+ with a new immediate value (atom, small integer, pid,
+ port).</p>
+ <p>
+ Own Id: OTP-14976</p>
+ </item>
+ <item>
+ <p>
+ <c>erlang:process_info/1</c> has been changed to no
+ longer include <c>messages</c> by default. Instead
+ <c>erlang:process_info/2</c> should be used.</p>
+ <p>
+ *** POTENTIAL INCOMPATIBILITY ***</p>
+ <p>
+ Own Id: OTP-14986 Aux Id: PR-1745 </p>
+ </item>
+ <item>
+ <p>
+ New NIF functions: <c>enif_mutex_name</c>,
+ <c>enif_cond_name</c>, <c>enif_rwlock_name</c>,
+ <c>enif_thread_name</c>, <c>enif_vfprintf</c>,
+ <c>enif_vsnprintf</c>.</p>
+ <p>
+ Own Id: OTP-14994</p>
+ </item>
+ <item>
+ <p>When <c>erlang:system_flag(backtrace_depth, 0)</c> has
+ been called, all exceptions will now contain the entry
+ for <em>one</em> function (despite the zero). It used to
+ be that a hand-made stack backtrace passed to
+ <c>erlang:raise/3</c> would be be truncated to an empty
+ list.</p>
+ <p>
+ Own Id: OTP-15026</p>
+ </item>
+ <item>
+ <p>
+ Fixed bug for named <c>ets</c> tables which could cause
+ unexpected results from matchspec iteration functions
+ (<c>ets:select*</c> and <c>ets:match*</c>) if the table
+ was deleted and recreated with the same name during the
+ iteration. The iteration could incorrectly continue
+ through the recreated table. The expected correct
+ behavior is now for the iteration call to fail with a
+ <c>badarg</c> exception if the table is deleted before
+ the iteration has completed.</p>
+ <p>
+ Own Id: OTP-15031</p>
+ </item>
+ <item>
+ <p>Two new guards BIFs operating on maps have been added:
+ <c>map_get/2</c> and <c>is_map_key/2</c>. They do the
+ same as <c>maps:get/2</c> and <c>maps:is_key/2</c>,
+ respectively, except that they are allowed to be used in
+ guards.</p>
+ <p>
+ Own Id: OTP-15037 Aux Id: PR-1784, PR-1802 </p>
+ </item>
+ <item>
+ <p>
+ Release run-queue lock while cleaning up terminated dirty
+ process.</p>
+ <p>
+ Own Id: OTP-15081</p>
+ </item>
+ <item>
+ <p>The callback module passed as <c>-epmd_module</c> to
+ erl has been expanded to be able to do name and port
+ resolving.</p> <p>Documentation has also been added in
+ the <seealso
+ marker="kernel:erl_epmd"><c>erl_epmd</c></seealso>
+ reference manual and ERTS User's Guide <seealso
+ marker="erts:alt_disco">How to Implement an Alternative
+ Service Discovery for Erlang Distribution</seealso>.</p>
+ <p>
+ Own Id: OTP-15086 Aux Id: PR-1694 </p>
+ </item>
+ </list>
+ </section>
+
+</section>
+
<section><title>Erts 9.3.1</title>
<section><title>Fixed Bugs and Malfunctions</title>