diff options
Diffstat (limited to 'erts/doc/src/erlang.xml')
| -rw-r--r-- | erts/doc/src/erlang.xml | 94 |
1 files changed, 60 insertions, 34 deletions
diff --git a/erts/doc/src/erlang.xml b/erts/doc/src/erlang.xml index 2e82bb62a9..6ed03f3dfc 100644 --- a/erts/doc/src/erlang.xml +++ b/erts/doc/src/erlang.xml @@ -59,6 +59,12 @@ </datatype> <datatype> + <name name="message_queue_data"></name> + <desc><p>See <seealso marker="#process_flag_message_queue_data"><c>erlang:process_flag(message_queue_data, MQD)</c></seealso>.</p> + </desc> + </datatype> + + <datatype> <name name="timestamp"></name> <desc><p>See <seealso marker="#timestamp/0">erlang:timestamp/0</seealso>.</p> </desc> @@ -4280,39 +4286,52 @@ os_prompt% </pre> <p>Returns the old value of the flag.</p> </desc> </func> - <marker id="process_flag_off_heap_message_queue"/> + <marker id="process_flag_message_queue_data"/> <func> <name name="process_flag" arity="2" clause_i="5"/> - <fsummary>Set process flag <c>off_heap_message_queue</c> for the calling process</fsummary> + <fsummary>Set process flag <c>message_queue_data</c> for the calling process</fsummary> + <type name="message_queue_data"/> <desc> <p>This flag determines how messages in the message queue are stored. When the flag is:</p> <taglist> - <tag><c>true</c></tag> + <tag><c>off_heap</c></tag> <item><p> <em>All</em> messages in the message queue will be stored outside of the process heap. This implies that <em>no</em> messages in the message queue will be part of a garbage collection of the process. </p></item> - <tag><c>false</c></tag> + <tag><c>on_heap</c></tag> + <item><p> + All messages in the message queue will eventually be + placed on heap. They may however temporarily be stored + off heap. This is how messages always have been stored + up until ERTS version 8.0. + </p></item> + <tag><c>mixed</c></tag> <item><p> Messages may be placed either on the heap or outside of the heap. </p></item> </taglist> <p> + The default <c>message_queue_data</c> process flag is determined + by the <seealso marker="erl#+xmqd"><c>+xmqd</c></seealso> + <c>erl</c> command line argument. + </p> + <p> If the process potentially may get a hugh amount of messages, - you are recommended to set the flag to <c>true</c>. This since - a garbage collection with lots of messages placed on the heap - may become extremly expensive. Performance of the actual - message passing is however generally better when setting the - flag to <c>false</c>. + you are recommended to set the flag to <c>off_heap</c>. This + since a garbage collection with lots of messages placed on + the heap may become extremly expensive and the process may + consume large amounts of memory. Performance of the + actual message passing is however generally better when not + using the <c>off_heap</c> flag. </p> <p> - When changing this flag from <c>false</c> to <c>true</c>, - all messages in the message queue are moved off heap. This - work has been initiated but not completed when this function + When changing this flag messages will be moved. This work + has been initiated but not completed when this function call returns. </p> <p>Returns the old value of the flag.</p> @@ -4478,6 +4497,7 @@ os_prompt% </pre> <type name="process_info_result_item"/> <type name="priority_level"/> <type name="stack_item"/> + <type name="message_queue_data" /> <desc> <p>Returns a list containing <c><anno>InfoTuple</anno></c>s with miscellaneous information about the process identified by @@ -4530,6 +4550,7 @@ os_prompt% </pre> <type name="process_info_result_item"/> <type name="stack_item"/> <type name="priority_level"/> + <type name="message_queue_data" /> <desc> <p>Returns information about the process identified by <c><anno>Pid</anno></c>, as specified by @@ -4698,13 +4719,14 @@ os_prompt% </pre> monitor by name, the list item is <c>{process, {<anno>RegName</anno>, <anno>Node</anno>}}</c>.</p> </item> - <tag><c>{off_heap_message_queue, <anno>OHMQ</anno>}</c></tag> + <tag><c>{message_queue_data, <anno>MQD</anno>}</c></tag> <item> - <p>Returns the current state of the <c>off_heap_message_queue</c> - process flag. <c><anno>OHMQ</anno></c> is either <c>true</c>, or - <c>false</c>. For more information, see the documentation of - <seealso marker="#process_flag_off_heap_message_queue"><c>process_flag(off_heap_message_queue, - OHMQ)</c></seealso>.</p> + <p>Returns the current state of the <c>message_queue_data</c> + process flag. <c><anno>MQD</anno></c> is either <c>off_heap</c>, + <c>on_heap</c>, or <c>mixed</c>. For more information, see the + documentation of + <seealso marker="#process_flag_message_queue_data"><c>process_flag(message_queue_data, + MQD)</c></seealso>.</p> </item> <tag><c>{priority, <anno>Level</anno>}</c></tag> <item> @@ -5474,6 +5496,7 @@ true</pre> <name name="spawn_opt" arity="2"/> <fsummary>Creates a new process with a fun as entry point.</fsummary> <type name="priority_level"/> + <type name="message_queue_data" /> <type name="spawn_opt_option" /> <desc> <p>Returns the process identifier (pid) of a new process @@ -5490,6 +5513,7 @@ true</pre> <name name="spawn_opt" arity="3"/> <fsummary>Creates a new process with a fun as entry point on a given node.</fsummary> <type name="priority_level"/> + <type name="message_queue_data" /> <type name="spawn_opt_option" /> <desc> <p>Returns the process identifier (pid) of a new process started @@ -5505,6 +5529,7 @@ true</pre> <name name="spawn_opt" arity="4"/> <fsummary>Creates a new process with a function as entry point.</fsummary> <type name="priority_level"/> + <type name="message_queue_data" /> <type name="spawn_opt_option" /> <desc> <p>Works as @@ -5607,17 +5632,17 @@ true</pre> fine-tuning an application and to measure the execution time with various <c><anno>VSize</anno></c> values.</p> </item> - <tag><c>{off_heap_message_queue, <anno>OHMQ</anno>}</c></tag> + <tag><c>{message_queue_data, <anno>MQD</anno>}</c></tag> <item> - <p>Sets the state of the <c>off_heap_message_queue</c> process - flag. <c><anno>OHMQ</anno></c> should be either <c>true</c>, or - <c>false</c>. The default <c>off_heap_message_queue</c> process - flag is determined by the - <seealso marker="erl#+xohmq"><c>+xohmq</c></seealso> <c>erl</c> + <p>Sets the state of the <c>message_queue_data</c> process + flag. <c><anno>MQD</anno></c> should be either <c>off_heap</c>, + <c>on_heap</c>, or <c>mixed</c>. The default + <c>message_queue_data</c> process flag is determined by the + <seealso marker="erl#+xmqd"><c>+xmqd</c></seealso> <c>erl</c> command line argument. For more information, see the documentation of - <seealso marker="#process_flag_off_heap_message_queue"><c>process_flag(off_heap_message_queue, - <anno>OHMQ</anno>)</c></seealso>.</p> + <seealso marker="#process_flag_message_queue_data"><c>process_flag(message_queue_data, + <anno>MQD</anno>)</c></seealso>.</p> </item> </taglist> </desc> @@ -5627,6 +5652,7 @@ true</pre> <name name="spawn_opt" arity="5"/> <fsummary>Creates a new process with a function as entry point on a given node.</fsummary> <type name="priority_level"/> + <type name="message_queue_data" /> <type name="spawn_opt_option" /> <desc> <p>Returns the process identifier (pid) of a new process started @@ -7106,15 +7132,15 @@ ok used by the runtime system. It is on the form "<major ver>.<minor ver>".</p> </item> - <tag><marker id="system_info_off_heap_message_queue"><c>off_heap_message_queue</c></marker></tag> + <tag><marker id="system_info_message_queue_data"><c>message_queue_data</c></marker></tag> <item> - <p>Returns the default value of the <c>off_heap_message_queue</c> - process flag which is either <c>true</c> or <c>false</c>. This - default is set by the <c>erl</c> command line argument - <seealso marker="erl#+xohmq"><c>+xohmq</c></seealso>. For more information on the - <c>off_heap_message_queue</c> process flag, see documentation of - <seealso marker="#process_flag_off_heap_message_queue"><c>process_flag(off_heap_message_queue, - OHMQ)</c></seealso>.</p> + <p>Returns the default value of the <c>message_queue_data</c> + process flag which is either <c>off_heap</c>, <c>on_heap</c>, or <c>mixed</c>. + This default is set by the <c>erl</c> command line argument + <seealso marker="erl#+xmqd"><c>+xmqd</c></seealso>. For more information on the + <c>message_queue_data</c> process flag, see documentation of + <seealso marker="#process_flag_message_queue_data"><c>process_flag(message_queue_data, + MQD)</c></seealso>.</p> </item> <tag><marker id="system_info_otp_release"><c>otp_release</c></marker></tag> <item> |