diff options
Diffstat (limited to 'erts/doc/src')
| -rw-r--r-- | erts/doc/src/erlang.xml | 358 | ||||
| -rw-r--r-- | erts/doc/src/notes.xml | 502 |
2 files changed, 189 insertions, 671 deletions
diff --git a/erts/doc/src/erlang.xml b/erts/doc/src/erlang.xml index 6ca57566aa..3fea64cef5 100644 --- a/erts/doc/src/erlang.xml +++ b/erts/doc/src/erlang.xml @@ -539,55 +539,94 @@ <name name="cancel_timer" arity="2"/> <fsummary>Cancel a timer</fsummary> <desc> - <p>Cancels a timer. <c><anno>TimerRef</anno></c> needs to refer to - a timer that was created by either - <seealso marker="#send_after/4"><c>erlang:send_after()</c></seealso>, - or <seealso marker="#start_timer/4"><c>erlang:start_timer()</c></seealso>.</p> - <p>Currently available <c><anno>Option</anno>s</c>:</p> + <p> + Cancels a timer that has been created by either + <seealso marker="#start_timer/4"><c>erlang:start_timer()</c></seealso>, + or <seealso marker="#send_after/4"><c>erlang:send_after()</c></seealso>. + <c><anno>TimerRef</anno></c> identifies the timer, and + was returned by the BIF that created the timer. + </p> + <p>Currently available <c><anno>Option</anno></c>s:</p> <taglist> <tag><c>{async, Async}</c></tag> <item> - <p>Asynchronous request for cancellation. <c>Async</c> - defaults to <c>false</c>. That is the operation will be - performed synchronously. When <c>Async</c> is set to - <c>true</c> the cancel operation will be performed - asynchronously. That is, <c>cancel_timer()</c> will send - a request for cancellation to the timer service that - manages the timer, and then return <c>ok</c>.</p></item> + <p> + Asynchronous request for cancellation. <c>Async</c> + defaults to <c>false</c> which will cause the + cancellation to be performed synchronously. When + <c>Async</c> is set to <c>true</c>, the cancel + operation will be performed asynchronously. That is, + <c>erlang:cancel_timer()</c> will send an asynchronous + request for cancellation to the timer service that + manages the timer, and then return <c>ok</c>. + </p> + </item> <tag><c>{info, Info}</c></tag> <item> - <p>Request information about the <c>Result</c> of the - cancellation. <c>Info</c> defaults to <c>true</c>. That - is information will be given. When <c>Info</c> is set to - <c>false</c> no information about the result of the cancel - operation will be given. When the operation is performed - synchronously the <c>Result</c> will returned from - <c>cancel_timer()</c>. When the operation is performed - asynchronously, a message on the form - <c>{cancel_timer, <anno>TimerRef</anno>, <anno>Result</anno>}</c> - will be sent to the caller of <c>cancel_timer()</c> when - the operation has been performed.</p></item> + <p> + Request information about the <c><anno>Result</anno></c> + of the cancellation. <c>Info</c> defaults to <c>true</c> + which means that the <c><anno>Result</anno></c> will + be given. When <c>Info</c> is set to <c>false</c>, no + information about the result of the cancellation + will be given. When the operation is performed</p> + <taglist> + <tag>synchronously</tag> + <item> + <p> + If <c>Info</c> is <c>true</c>, the <c>Result</c> will + returned by <c>erlang:cancel_timer()</c>; otherwise, + <c>ok</c> will be returned. + </p> + </item> + <tag>asynchronously</tag> + <item> + <p> + If <c>Info</c> is <c>true</c>, a message on the form + <c>{cancel_timer, <anno>TimerRef</anno>, + <anno>Result</anno>}</c> will be sent to the + caller of <c>erlang:cancel_timer()</c> when the + cancellation operation has been performed; otherwise, + no message will be sent. + </p> + </item> + </taglist> + </item> </taglist> - <p>When the <c><anno>Result</anno></c> equals <c>false</c> a timer - corresponding to <c><anno>TimerRef</anno></c> could not be found. This - can be either because the timer had expired, been canceled, or because - <c><anno>TimerRef</anno></c> do not correspond to a timer. When the - <c><anno>Result</anno></c> is an integer, it represents - the time in milli seconds left before the timer will expire.</p> - <note><p>The timer service that manages the timer may be co-located - with another scheduler than the scheduler that the calling process - is executing on. In this case communication with the timer - service will be performed using asynchronous signals. If the calling - process is in critical path and can do other things while waiting - for the result of this operation, you want to use the <c>{async, true}</c> - option.</p></note> + <p> + More <c><anno>Option</anno></c>s may be added in the future. + </p> + <p> + When the <c><anno>Result</anno></c> equals <c>false</c>, a + timer corresponding to <c><anno>TimerRef</anno></c> could not + be found. This can be either because the timer had expired, + already had been canceled, or because <c><anno>TimerRef</anno></c> + never has corresponded to a timer. If the timer has expired, + the timeout message has been sent, but it does not tell you + whether or not it has arrived at its destination yet. When the + <c><anno>Result</anno></c> is an integer, it represents the + time in milli-seconds left until the timer will expire. + </p> + <note> + <p> + The timer service that manages the timer may be co-located + with another scheduler than the scheduler that the calling + process is executing on. If this is the case, communication + with the timer service will take much longer time than if it + is located locally. If the calling process is in critical + path, and can do other things while waiting for the result + of this operation, or is not interested in the result of + the operation, you want to use the <c>{async, true}</c> + option. If using the <c>{async, false}</c> option, the calling + process will be blocked until the operation has been + performed. + </p> + </note> <p>See also <seealso marker="#send_after/4"><c>erlang:send_after/4</c></seealso>, <seealso marker="#start_timer/4"><c>erlang:start_timer/4</c></seealso>, and <seealso marker="#read_timer/2"><c>erlang:read_timer/2</c></seealso>.</p> - <p>Note: Cancelling a timer does not guarantee that the message - has not already been delivered to the message queue.</p> </desc> </func> <func> @@ -596,7 +635,7 @@ <desc> <p>Cancels a timer. The same as calling <seealso marker="#cancel_timer/2"><c>erlang:cancel_timer(TimerRef, - [{async, false}, {info, true}])</c></seealso>.</p> + [])</c></seealso>.</p> </desc> </func> <func> @@ -4548,37 +4587,60 @@ os_prompt% </pre> <name name="read_timer" arity="2"/> <fsummary>Read the state of a timer</fsummary> <desc> - <p>Read the state of a timer. <c><anno>TimerRef</anno></c> - needs to refer to a timer that was created by either - <seealso marker="#send_after/4"><c>erlang:send_after()</c></seealso>, - or <seealso marker="#start_timer/4"><c>erlang:start_timer()</c></seealso>.</p> + <p> + Read the state of a timer that has been created by either + <seealso marker="#start_timer/4"><c>erlang:start_timer()</c></seealso>, + or <seealso marker="#send_after/4"><c>erlang:send_after()</c></seealso>. + <c><anno>TimerRef</anno></c> identifies the timer, and + was returned by the BIF that created the timer. + </p> <p>Currently available <c><anno>Option</anno>s</c>:</p> <taglist> <tag><c>{async, Async}</c></tag> <item> - <p>Asynchronous request. <c>Async</c> defaults to <c>false</c>. That - is the operation will be performed synchronously, and the <c>Result</c> - will returned from <c>read_timer()</c>. When <c>Async</c> is set to - <c>true</c>, <c>read_timer()</c> will send a request for the - <c>Result</c> to a timer service that manages the timer and then - return <c>ok</c>. A message on the format - <c>{read_timer, <anno>TimerRef</anno>, <anno>Result</anno>}</c> - will be sent to the caller of <c>read_timer()</c> when - the operation has been processed.</p></item> + <p> + Asynchronous request for state information. <c>Async</c> + defaults to <c>false</c> which will cause the operation + to be performed synchronously. In this case, the <c>Result</c> + will be returned by <c>erlang:read_timer()</c>. When + <c>Async</c> is set to <c>true</c>, <c>erlang:read_timer()</c> + will send an asynchronous request for the state information + to the timer service that manages the timer, and then return + <c>ok</c>. A message on the format <c>{read_timer, + <anno>TimerRef</anno>, <anno>Result</anno>}</c> will be + sent to the caller of <c>erlang:read_timer()</c> when the + operation has been processed. + </p> + </item> </taglist> - <p>When the <c><anno>Result</anno></c> equals <c>false</c> a timer - corresponding to <c><anno>TimerRef</anno></c> could not be found. This - can be either because the timer had expired, been canceled, or because - <c><anno>TimerRef</anno></c> do not correspond to a timer. When the - <c><anno>Result</anno></c> is an integer, it represents - the time in milli seconds left before the timer will expire.</p> - <note><p>The timer service that manages the timer may be co-located - with another scheduler than the scheduler that the calling process - is executing on. In this case communication with the timer - service will be performed using asynchronous signals. If the calling - process is in critical path and can do other things while waiting - for the result of this operation, you want to use the <c>{async, true}</c> - option.</p></note> + <p> + More <c><anno>Option</anno></c>s may be added in the future. + </p> + <p> + When the <c><anno>Result</anno></c> equals <c>false</c>, a + timer corresponding to <c><anno>TimerRef</anno></c> could not + be found. This can be either because the timer had expired, + had been canceled, or because <c><anno>TimerRef</anno></c> + never has corresponded to a timer. If the timer has expired, + the timeout message has been sent, but it does not tell you + whether or not it has arrived at its destination yet. When the + <c><anno>Result</anno></c> is an integer, it represents the + time in milli-seconds left until the timer will expire. + </p> + <note> + <p> + The timer service that manages the timer may be co-located + with another scheduler than the scheduler that the calling + process is executing on. If this is the case, communication + with the timer service will take much longer time than if it + is located locally. If the calling process is in critical + path, and can do other things while waiting for the result + of this operation you want to use the <c>{async, true}</c> + option. If using the <c>{async, false}</c> option, the calling + process will be blocked until the operation has been + performed. + </p> + </note> <p>See also <seealso marker="#send_after/4"><c>erlang:send_after/4</c></seealso>, <seealso marker="#start_timer/4"><c>erlang:start_timer/4</c></seealso>, @@ -4592,7 +4654,7 @@ os_prompt% </pre> <desc> <p>Read the state of a timer. The same as calling <seealso marker="#read_timer/2"><c>erlang:read_timer(TimerRef, - [{async, false}])</c></seealso>.</p> + [])</c></seealso>.</p> </desc> </func> <func> @@ -4744,48 +4806,14 @@ true</pre> <name name="send_after" arity="4"/> <fsummary>Start a timer</fsummary> <desc> - <p>Starts a timer. When the timer expires, the message - <c><anno>Msg</anno></c> will be sent to - <c><anno>Dest</anno></c>.</p> - <p>If <c><anno>Dest</anno></c> is a <c>pid()</c> it has to - be a <c>pid()</c> of a local process, dead or alive.</p> - <p>Currently available <c><anno>Option</anno>s</c>:</p> - <taglist> - <tag><c>{abs, Abs}</c></tag> - <item> - <p>Absolute timeout. When <c>Abs</c> is <c>false</c> - the <c><anno>Time</anno></c> value will be interpreted - as a time in milli-seconds relative current - <seealso marker="time_correction#Erlang_Monotonic_Time">Erlang - monotonic time</seealso>. When <c>Abs</c> is <c>true</c> the - <c><anno>Time</anno></c> value will be interpreted as an absolute - Erlang monotonic time of milli second time unit. <c>Abs</c> - defaults to <c>false</c>.</p> - </item> - </taglist> - <p>The absolute time when the timer is set to expire needs - to be in the range between - <seealso marker="#system_info_start_time"><c>erlang:system_info(start_time)</c></seealso> - and - <seealso marker="#system_info_end_time"><c>erlang:system_info(end_time)</c></seealso>. - If a negative relative time is specified the time is not - allowed to be negative.</p> - <p>If <c><anno>Dest</anno></c> is an <c>atom()</c>, it is supposed to be the name of - a registered process. The process referred to by the name is - looked up at the time of delivery. No error is given if - the name does not refer to a process.</p> - <p>If <c><anno>Dest</anno></c> is a <c>pid()</c>, the timer will be automatically - canceled if the process referred to by the <c>pid()</c> is not alive, - or when the process exits. This feature was introduced in - erts version 5.4.11. Note that timers will not be - automatically canceled when <c><anno>Dest</anno></c> is an <c>atom()</c>.</p> - <p>See also - <seealso marker="#start_timer/4"><c>erlang:send_timer/4</c></seealso>, - <seealso marker="#cancel_timer/2"><c>erlang:cancel_timer/2</c></seealso>, - and - <seealso marker="#read_timer/2"><c>erlang:read_timer/2</c></seealso>.</p> - <p>Failure: <c>badarg</c> if the arguments does not satisfy - the requirements specified above.</p> + <p> + Starts a timer. When the timer expires, the message + <c><anno>Msg</anno></c> will be sent to the process + identified by <c><anno>Dest</anno></c>. Appart from + the format of the message sent to + <c><anno>Dest</anno></c> when the timer expires + <c>erlang:send_after/4</c> works exactly as + <seealso marker="#start_timer/4"><c>erlang:start_timer/4</c></seealso>.</p> </desc> </func> <func> @@ -4793,36 +4821,8 @@ true</pre> <fsummary>Start a timer</fsummary> <desc> <p>Starts a timer. The same as calling - <seealso marker="#send_timer/4"><c>erlang:send_after(<anno>Time</anno>, - <anno>Dest</anno>, <anno>Msg</anno>, [{abs, false}])</c></seealso>.</p> - </desc> - </func> - <func> - <name name="send_after" arity="3"/> - <type_desc variable="Time">0 <= Time <= 4294967295</type_desc> - <fsummary>Start a timer</fsummary> - <desc> - <p>Starts a timer which will send the message <c>Msg</c> - to <c><anno>Dest</anno></c> after <c><anno>Time</anno></c> milliseconds.</p> - <p>If <c><anno>Dest</anno></c> is a <c>pid()</c> it has to be a <c>pid()</c> of a local process, dead or alive.</p> - <p>The <c><anno>Time</anno></c> value can, in the current implementation, not be greater than 4294967295.</p> - <p>If <c><anno>Dest</anno></c> is an <c>atom()</c>, it is supposed to be the name of - a registered process. The process referred to by the name is - looked up at the time of delivery. No error is given if - the name does not refer to a process.</p> - - <p>If <c><anno>Dest</anno></c> is a <c>pid()</c>, the timer will be automatically - canceled if the process referred to by the <c>pid()</c> is not alive, - or when the process exits. This feature was introduced in - erts version 5.4.11. Note that timers will not be - automatically canceled when <c><anno>Dest</anno></c> is an <c>atom</c>.</p> - <p>See also - <seealso marker="#start_timer/3">erlang:start_timer/3</seealso>, - <seealso marker="#cancel_timer/2">erlang:cancel_timer/2</seealso>, - and - <seealso marker="#read_timer/2">erlang:read_timer/2</seealso>.</p> - <p>Failure: <c>badarg</c> if the arguments does not satisfy - the requirements specified above.</p> + <seealso marker="#send_after/4"><c>erlang:send_after(<anno>Time</anno>, + <anno>Dest</anno>, <anno>Msg</anno>, [])</c></seealso>.</p> </desc> </func> <func> @@ -5231,41 +5231,59 @@ true</pre> <name name="start_timer" arity="4"/> <fsummary>Start a timer</fsummary> <desc> - <p>Starts a timer. When the timer expires, the message + <p> + Starts a timer. When the timer expires, the message <c>{timeout, <anno>TimerRef</anno>, <anno>Msg</anno>}</c> - will be sent to <c><anno>Dest</anno></c>.</p> - <p>If <c><anno>Dest</anno></c> is a <c>pid()</c> it has to - be a <c>pid()</c> of a local process, dead or alive.</p> - <p>Currently available <c><anno>Option</anno>s</c>:</p> + will be sent to the process identified by + <c><anno>Dest</anno></c>. + </p> + <p>Currently available <c><anno>Option</anno></c>s:</p> <taglist> <tag><c>{abs, Abs}</c></tag> <item> - <p>Absolute timeout. When <c>Abs</c> is <c>false</c> - the <c><anno>Time</anno></c> value will be interpreted - as a time in milli-seconds relative current - <seealso marker="time_correction#Erlang_Monotonic_Time">Erlang - monotonic time</seealso>. When <c>Abs</c> is <c>true</c> the - <c><anno>Time</anno></c> value will be interpreted as an absolute - Erlang monotonic time of milli second time unit. <c>Abs</c> - defaults to <c>false</c>.</p> + <p> + Absolute <c><anno>Time</anno></c> value. <c>Abs</c> + defaults to <c>false</c> which means that the + <c><anno>Time</anno></c> value will be interpreted + as a time in milli-seconds relative current + <seealso marker="time_correction#Erlang_Monotonic_Time">Erlang + monotonic time</seealso>. When <c>Abs</c> is set to + <c>true</c>, the <c><anno>Time</anno></c> value will + be interpreted as an absolute Erlang monotonic time of + milli-seconds + <seealso marker="#type_time_unit">time unit</seealso>. + </p> </item> </taglist> - <p>The absolute time when the timer is set to expire needs - to be in the range between - <seealso marker="#system_info_start_time"><c>erlang:system_info(start_time)</c></seealso> - and - <seealso marker="#system_info_end_time"><c>erlang:system_info(end_time)</c></seealso>. - If a negative relative time is specified the time is not - allowed to be negative.</p> - <p>If <c><anno>Dest</anno></c> is an <c>atom()</c>, it is supposed to be the name of - a registered process. The process referred to by the name is - looked up at the time of delivery. No error is given if - the name does not refer to a process.</p> - <p>If <c><anno>Dest</anno></c> is a <c>pid()</c>, the timer will be automatically - canceled if the process referred to by the <c>pid()</c> is not alive, - or when the process exits. This feature was introduced in - erts version 5.4.11. Note that timers will not be - automatically canceled when <c><anno>Dest</anno></c> is an <c>atom()</c>.</p> + <p> + More <c><anno>Option</anno></c>s may be added in the future. + </p> + <p> + The absolute point in time that the timer is set to expire on + has to be in the interval + <c>[</c><seealso marker="#system_info_start_time"><c>erlang:system_info(start_time)</c></seealso><c>, + </c><seealso marker="#system_info_end_time"><c>erlang:system_info(end_time)</c></seealso><c>]</c>. + Further, if a relative time is specified, the <c><anno>Time</anno></c> value + is not allowed to be negative. + </p> + <p> + If <c><anno>Dest</anno></c> is a <c>pid()</c>, it has to + be a <c>pid()</c> of a process created on the current + runtime system instance. This process may or may not + have terminated. If <c><anno>Dest</anno></c> is an + <c>atom()</c>, it will be interpreted as the name of a + locally registered process. The process referred to by the + name is looked up at the time of timer expiration. No error + is given if the name does not refer to a process. + </p> + <p> + If <c><anno>Dest</anno></c> is a <c>pid()</c>, the timer will + be automatically canceled if the process referred to by the + <c>pid()</c> is not alive, or when the process exits. This + feature was introduced in erts version 5.4.11. Note that + timers will not be automatically canceled when + <c><anno>Dest</anno></c> is an <c>atom()</c>. + </p> <p>See also <seealso marker="#send_after/4"><c>erlang:send_after/4</c></seealso>, <seealso marker="#cancel_timer/2"><c>erlang:cancel_timer/2</c></seealso>, @@ -5281,7 +5299,7 @@ true</pre> <desc> <p>Starts a timer. The same as calling <seealso marker="#start_timer/4"><c>erlang:start_timer(<anno>Time</anno>, - <anno>Dest</anno>, <anno>Msg</anno>, [{abs, false}])</c></seealso>.</p> + <anno>Dest</anno>, <anno>Msg</anno>, [])</c></seealso>.</p> </desc> </func> <func> @@ -6845,7 +6863,9 @@ ok <item><p>The <seealso marker="#monotonic_time/0">Erlang monotonic time</seealso> in <c>native</c> <seealso marker="#type_time_unit">time unit</seealso> at the - time when current Erlang runtime system instance started.</p></item> + time when current Erlang runtime system instance started. See also + <seealso marker="#system_info_end_time"><c>erlang:system_info(end_time)</c></seealso>. + </p></item> <tag><c>system_version</c></tag> <item> <p>Returns a string containing version number and diff --git a/erts/doc/src/notes.xml b/erts/doc/src/notes.xml index c85cbe543d..35e6e55e72 100644 --- a/erts/doc/src/notes.xml +++ b/erts/doc/src/notes.xml @@ -30,508 +30,6 @@ </header> <p>This document describes the changes made to the ERTS application.</p> -<section><title>Erts 7.0</title> - - <section><title>Fixed Bugs and Malfunctions</title> - <list> - <item> - <p> - Fix issuing with spaces and quoting in the arguments when - using erlang:open_port spawn_executable on windows. The - behavior now mimics how unix works. This change implies a - backwards incompatibility for how spawn_executable works - on windows.</p> - <p> - *** POTENTIAL INCOMPATIBILITY ***</p> - <p> - Own Id: OTP-11905</p> - </item> - <item> - <p> - Fix global call trace when hipe compiled code call beam - compiled functions. Tracing of beam functions should now - alway work regardless who the caller is.</p> - <p> - Own Id: OTP-11939</p> - </item> - <item> - <p> - Correct cache alignment for ETS <c>write_concurrency</c> - locks to improve performance by reduced false sharing. - May increase memory footprint for tables with - <c>write_concurrency</c>.</p> - <p> - Own Id: OTP-11974</p> - </item> - <item> - <p> - All possibly blocking operations in the fd/spawn and - terminal driver have been converted to non-blocking - operations. Before this fix it was possible for the VM to - be blocked for a long time if the entity consuming - stdout/stderr did not consume it fast enough.</p> - <p> - Own Id: OTP-12239</p> - </item> - <item> - <p> - Add missing overhead for offheap binaries created from - external format. This fix can improve the garbage - collection of large binaries originating from - <c>binary_to_term</c> or messages from remote nodes.</p> - <p> - Own Id: OTP-12554</p> - </item> - <item> - <p> - Ensure hashing of zero is consistent</p> - <p> Erlang treats positive and negative zero as - equal:</p> - <p> - <c>true = 0.0 =:= 0.0/-1</c></p> - <p>However, Erlangs hash functions: hash, phash and - phash2 did not reflect this behaviour. The hash values - produced by the different hash functions would not be - identical for positive and negative zero.</p> <p>This - change ensures that hash value of positive zero is always - produced regardless of the signedness of the zero float, - i.e.,</p> - <p> - <c>true = erlang:phash2(0.0) =:= - erlang:phash2(0.0/-1)</c></p> - <p> - Own Id: OTP-12641</p> - </item> - <item> - <p> - Ensure NIF term creation disallows illegal floating point - values and too long atoms. Such values will cause a NIF - to throw badarg exception when it returns.</p> - <p> - Own Id: OTP-12655</p> - </item> - <item> - <p> - Fixed building of Map results from match_specs</p> - <p> - A faulty "box-value" entered into the heap which could - cause a segmentation fault in the garbage collector if it - was written on a heap fragment.</p> - <p> - Own Id: OTP-12656</p> - </item> - <item> - <p> - Fix hipe bug when matching a "writable" binary. The bug - has been seen to sometimes cause a failed binary matching - of a correct utf8 character, but other symptoms are also - possible.</p> - <p> - Own Id: OTP-12667</p> - </item> - <item> - <p> - Keep dirty schedulers from waking other schedulers.</p> - <p> - Own Id: OTP-12685</p> - </item> - <item> - <p> - Disable floating point exceptions if the VM is compiled - by clang/llvm. This is a known long-standing problem in - clang/llvm.</p> - <p> - Own Id: OTP-12717</p> - </item> - <item> - <p> - Fix bug in <c>file:sendfile</c> for FreeBSD causing not - the entire file to be sent.</p> - <p> - Own Id: OTP-12720</p> - </item> - </list> - </section> - - - <section><title>Improvements and New Features</title> - <list> - <item> - <p> - Add <c>md5</c> and <c>module</c> entries to - <c>?MODULE:module_info/0/1</c> and remove obsolete entry - 'import'.</p> - <p> - *** POTENTIAL INCOMPATIBILITY ***</p> - <p> - Own Id: OTP-11940</p> - </item> - <item> - <p> - Debug function <c>erlang:display/1</c> shows content of - binaries and bitstrings, not only the length.</p> - <p> - Own Id: OTP-11941</p> - </item> - <item> - <p>The time functionality of Erlang has been extended. - This both includes a <seealso - marker="time_correction#The_New_Time_API">new - API</seealso> for time, as well as <seealso - marker="time_correction#Time_Warp_Modes">time warp - modes</seealso> which alters the behavior of the system - when system time changes. <em>You are strongly encouraged - to use the new API</em> instead of the old API based on - <seealso - marker="erlang#now/0"><c>erlang:now/0</c></seealso>. - <c>erlang:now/0</c> has been deprecated since it is and - forever will be a scalability bottleneck. For more - information see the <seealso - marker="time_correction">Time and Time - Correction</seealso> chapter of the ERTS User's - Guide.</p> - <p>Besides the API changes and time warp modes a lot of - scalability and performance improvements regarding time - management has been made internally in the runtime - system. Examples of such improvements are scheduler - specific timer wheels, scheduler specific BIF timer - management, parallel retrieval of monotonic time and - system time on systems with primitives that are not - buggy.</p> - <p> - Own Id: OTP-11997</p> - </item> - <item> - <p><c>erlang:function_exported(M, F, A)</c> will now - return <c>true</c> if <c>M:F/A</c> refers to a BIF.</p> - <p> - *** POTENTIAL INCOMPATIBILITY ***</p> - <p> - Own Id: OTP-12099</p> - </item> - <item> - <p> - New BIF: <c>erlang:get_keys/0</c>, lists all keys - associated with the process dictionary. Note: - <c>erlang:get_keys/0</c> is auto-imported.</p> - <p> - *** POTENTIAL INCOMPATIBILITY ***</p> - <p> - Own Id: OTP-12151 Aux Id: seq12521 </p> - </item> - <item> - <p> - Make distributed send of large messages yield to improve - real-time characteristics.</p> - <p> - Own Id: OTP-12232</p> - </item> - <item> - <p> - Use high accuracy poll timeouts</p> - <p> - Where available, use poll/select API's that can handle - time resolutions less than 1ms. In the cases where such - API's are not available the timeout is rounded up to the - nearest ms.</p> - <p> - Own Id: OTP-12236</p> - </item> - <item> - <p> - The internal group to user_drv protocol has been changed - to be synchronous in order to guarantee that output sent - to a process implementing the user_drv protocol is - printed before replying. This protocol is used by the - standard_output device and the ssh application when - acting as a client. </p> - <p> - This change changes the previous unlimited buffer when - printing to standard_io and other devices that end up in - user_drv to 1KB.</p> - <p> - *** POTENTIAL INCOMPATIBILITY ***</p> - <p> - Own Id: OTP-12240</p> - </item> - <item> - <p>The previously introduced "eager check I/O" feature is - now enabled by default.</p> - <p>Eager check I/O can be disabled using the <c>erl</c> - command line argument: <seealso - marker="erl#+secio"><c>+secio false</c></seealso></p> - <p>Characteristics impact compared to previous - default:</p> <list> <item>Lower latency and smoother - management of externally triggered I/O operations.</item> - <item>A slightly reduced priority of externally triggered - I/O operations.</item> </list> - <p> - Own Id: OTP-12254 Aux Id: OTP-12117 </p> - </item> - <item> - <p> - Properly support maps in match_specs</p> - <p> - Own Id: OTP-12270</p> - </item> - <item> - <p> - The notice that a crashdump has been written has been - moved to be printed before the crashdump is generated - instead of afterwords. The wording of the notice has also - been changed.</p> - <p> - *** POTENTIAL INCOMPATIBILITY ***</p> - <p> - Own Id: OTP-12292</p> - </item> - <item> - <p> - New function <c>ets:take/2</c>. Works the same as - <c>ets:delete/2</c> but also returns the deleted - object(s).</p> - <p> - Own Id: OTP-12309</p> - </item> - <item> - <p> - Tracing with cpu_timestamp option has been enabled on - Linux.</p> - <p> - Own Id: OTP-12366</p> - </item> - <item> - <p> - ets:info/1,2 now contains information about whether - write_concurrency or read_concurrency is enabled.</p> - <p> - Own Id: OTP-12376</p> - </item> - <item> - <p> - Improved usage of <c>gcc</c>'s builtins for atomic memory - access. These are used when no other implementation of - atomic memory operations is available. For example, when - compiling for ARM when <c>libatomic_ops</c> is not - available.</p> - <p> - The largest improvement will be seen when compiling with - a <c>gcc</c> with support for the <c>__atomic_*</c> - builtins (using a <c>gcc</c> of at least version 4.7), - but also when only the legacy <c>__sync_*</c> builtins - are available (using a <c>gcc</c> of at least version - 4.1) an improvement can be seen.</p> - <p> - For more information see the "<seealso - marker="doc/installation_guide:INSTALL#Advanced-configuration-and-build-of-ErlangOTP_Configuring_Atomic-Memory-Operations-and-the-VM">Atomic - Memory Operations and the VM</seealso>" section of - <c>$ERL_TOP/HOWTO/INSTALL.md</c>.</p> - <p> - Own Id: OTP-12383</p> - </item> - <item> - <p> - Introduce <c>math:log2/1</c> function to math module.</p> - <p> - Own Id: OTP-12411</p> - </item> - <item> - <p> - Remove perfctr support</p> - <p> - Development of perfctr in the linux kernel ceased in - 2010. The perfctr support code in the Erlang VM is thus - effectively dead code and therefor removed.</p> - <p> - Own Id: OTP-12508</p> - </item> - <item> - <p><c>zlib:inflateChunk/2</c> has been added. It works - like <c>zlib:inflate/2</c>, but decompresses no more data - than will fit in the buffer configured by - <c>zlib:setBufSize/2</c>.</p> - <p> - Own Id: OTP-12548</p> - </item> - <item> - <p> - Use linear search for small select_val arrays</p> - <p> - Own Id: OTP-12555</p> - </item> - <item> - <p> - New BIF ets:update_counter/4 with a default object as - argument, which will be inserted in the table if the key - was not found.</p> - <p> - Own Id: OTP-12563</p> - </item> - <item> - <p> - Export missing types from zlib module</p> - <p> - Own Id: OTP-12584</p> - </item> - <item> - <p> - Use persistent hashmaps for large Maps <p>Maps will use a - persistent hashmap implementation when the number of - pairs in a Map becomes sufficiently large. The change - will occur when a Map reaches 33 pairs in size but this - limit might change in the future.</p></p> - <p>The most significant impact for the user by this - change is speed, and to a lesser degree memory - consumption and introspection of Maps. Memory consumption - size is probalistic but lesser than <c>gb_trees</c> or - <c>dict</c> for instance. Any other impacts will be - transparent for the user except for the following - changes.</p> - <p>Semantics of Maps have changed in two incompatible - ways compared to the experimental implementation in OTP - 17:</p> <list> <item>Hashing of maps is done different by - <c>erlang:phash2/1,2</c>, <c>erlang:phash/1</c> and - <c>erlang:hash/2</c>.</item> <item>Comparing two maps - with ==, /=, =<, <, >= and >, is done - different if the keys contain floating point - numbers.</item> </list> - <p> - *** POTENTIAL INCOMPATIBILITY ***</p> - <p> - Own Id: OTP-12585</p> - </item> - <item> - <p> - Scalability improvement for <seealso - marker="erlang#make_ref/0">erlang:make_ref/0</seealso>, - and other functionality that create references. Each - scheduler now manage its own set of references. By this - no communication at all is needed when creating - references.</p> - <p> - Previous implementation generated a strictly - monotonically increasing sequence of references - corresponding to creation time on the runtime system - instance. This is <em>not</em> the case with current - implementation. You can only expect reference to be - unique. The Erlang/OTP documentation has never mentioned - anything else but the uniqueness property, so this change - <em>is</em> fully compatible. The only reason we've - marked this as a potential incompatibility is since an - early draft for an Erlang specification mentions strict - monotonicity as a property.</p> - <p> - If you need to create data with a strict monotonicity - property use <seealso - marker="erlang#unique_integer/1">erlang:unique_integer([monotonic])</seealso>. - Do <em>not</em> use the deprecated <seealso - marker="erlang:now/0">erlang:now()</seealso>.</p> - <p> - *** POTENTIAL INCOMPATIBILITY ***</p> - <p> - Own Id: OTP-12610</p> - </item> - <item> - <p> - Enable different abort signal from heart</p> - <p>By using environment variable HEART_KILL_SIGNAL, heart - can now use a different signal to kill the old running - Erlang.</p> - <p>By default the signal is SIGKILL but SIGABRT may also - be used by setting environment variable: - HEART_KILL_SIGNAL=SIGABRT</p> - <p> - Own Id: OTP-12613 Aux Id: seq12826 </p> - </item> - <item> - <p> - Update autconf to latest version 2015-03-04</p> - <p> - Own Id: OTP-12646</p> - </item> - <item> - <p> - Optimization of timers internally in the VM. This include - process timers (<c>receive ... after</c>), port timers - (<c>driver_set_timer()</c>) as well as BIF timers - (<c>erlang:send_after()</c>/<c>erlang:start_timer()</c>).</p> - <p> - Each scheduler thread now has its own lock-free timer - service instead of one locked central service. This - dramatically improves performance of timer management on - systems with a large amount of schedulers and timers.</p> - <p> - The timer service internal data structure has also been - optimized to be able to handle more timers than before. - That is, each timer service is by its self able to handle - more timers without dramatic performance loss than the - old centralized timer service.</p> - <p> - The API of BIF timers has also been extended. Timeout - values are for example no longer limited to 32-bit - integers. For more information see the documentation of - <seealso - marker="erlang#start_timer/4"><c>erlang:start_timer/4</c></seealso>, - <seealso - marker="erlang#send_after/4"><c>erlang:send_after/4</c></seealso>, - <seealso - marker="erlang#cancel_timer/2"><c>erlang:cancel_timer/2</c></seealso>, - and <seealso - marker="erlang#read_timer/2"><c>erlang:read_timer/2</c></seealso>.</p> - <p> - Own Id: OTP-12650 Aux Id: OTP-11997 </p> - </item> - <item> - <p> - Specialize instructions from common assembler patterns</p> - <p>Specialize common instructions of <c>rem</c>, - <c>band</c>, <c>minus</c> and <c>plus</c> in the beam - loader. This will reduce the number of fetches and thus - lessen the instruction dispatch pressure during runtime - and speed up those operations in some common cases.</p> - <p>Specialize move patterns from x-registers to the stack - with a new <c>move_window</c> instruction. This change - will reduce instruction dispatch pressure.</p> - <p> - Own Id: OTP-12690</p> - </item> - <item> - <p> - Fix cross compilation for Android.</p> - <p> - Own Id: OTP-12693</p> - </item> - <item> - <p> - Fix incorrect use of autoconf macro AC_EGREP_CPP, which - could cause faulty configuration if run from a path - containing the string 'yes'.</p> - <p> - Own Id: OTP-12706</p> - </item> - <item> - <p> - Minimal Java version is now 1.6</p> - <p> - Own Id: OTP-12718</p> - </item> - <item> - <p> - Send format and args on process exit to error_logger</p> - <p> - Previously, the emulator would generate a whole string - with values and call the error_logger passing - <c>"~s~n"</c>. This changes it to a format string - containing <c>~p</c> with the respective values as - arguments.</p> - <p> - Own Id: OTP-12735</p> - </item> - </list> - </section> - -</section> - <section><title>Erts 6.4.1</title> <section><title>Fixed Bugs and Malfunctions</title> |