diff options
Diffstat (limited to 'erts/doc/src/erlang.xml')
| -rw-r--r-- | erts/doc/src/erlang.xml | 114 |
1 files changed, 109 insertions, 5 deletions
diff --git a/erts/doc/src/erlang.xml b/erts/doc/src/erlang.xml index 13b16d1ed3..c3e2ed61e9 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> @@ -1105,7 +1111,7 @@ <fsummary>Prints a term on standard output.</fsummary> <desc> <p>Prints a text representation of <c><anno>Term</anno></c> on the - standard output. On OSE, the term is printed to the ramlog.</p> + standard output.</p> <warning> <p>This BIF is intended for debugging only.</p> </warning> @@ -4280,9 +4286,59 @@ os_prompt% </pre> <p>Returns the old value of the flag.</p> </desc> </func> - + <marker id="process_flag_message_queue_data"/> <func> <name name="process_flag" arity="2" clause_i="5"/> + <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>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>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>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 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> + </desc> + </func> + <func> + <name name="process_flag" arity="2" clause_i="6"/> <fsummary>Sets process flag <c>priority</c> for the calling process.</fsummary> <type name="priority_level"/> <desc> @@ -4356,7 +4412,7 @@ os_prompt% </pre> </func> <func> - <name name="process_flag" arity="2" clause_i="6"/> + <name name="process_flag" arity="2" clause_i="7"/> <fsummary>Sets process flag <c>save_calls</c> for the calling process.</fsummary> <desc> <p><c><anno>N</anno></c> must be an integer in the interval 0..10000. @@ -4387,7 +4443,7 @@ os_prompt% </pre> </func> <func> - <name name="process_flag" arity="2" clause_i="7"/> + <name name="process_flag" arity="2" clause_i="8"/> <fsummary>Sets process flag <c>sensitive</c> for the calling process.</fsummary> <desc> <p>Sets or clears flag <c>sensitive</c> for the current process. @@ -4441,6 +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 @@ -4493,6 +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 @@ -4661,6 +4719,15 @@ os_prompt% </pre> monitor by name, the list item is <c>{process, {<anno>RegName</anno>, <anno>Node</anno>}}</c>.</p> </item> + <tag><c>{message_queue_data, <anno>MQD</anno>}</c></tag> + <item> + <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> <p><c><anno>Level</anno></c> is the current priority level for @@ -4803,6 +4870,12 @@ os_prompt% </pre> <seealso marker="kernel:code">code(3)</seealso>) and is not to be used elsewhere.</p> </warning> + <note> + <p>As from <c>ERTS</c> 8.0 (OTP 19), any lingering processes + that still execute the old code will be killed by this function. + In earlier versions, such incorrect use could cause much + more fatal failures, like emulator crash.</p> + </note> <p>Failure: <c>badarg</c> if there is no old code for <c><anno>Module</anno></c>.</p> </desc> @@ -5429,6 +5502,8 @@ 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 started by the application of <c><anno>Fun</anno></c> @@ -5444,6 +5519,8 @@ 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 by the application of <c><anno>Fun</anno></c> to the @@ -5458,6 +5535,8 @@ 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 <seealso marker="#spawn/3">spawn/3</seealso>, except that an @@ -5559,6 +5638,18 @@ true</pre> fine-tuning an application and to measure the execution time with various <c><anno>VSize</anno></c> values.</p> </item> + <tag><c>{message_queue_data, <anno>MQD</anno>}</c></tag> + <item> + <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_message_queue_data"><c>process_flag(message_queue_data, + <anno>MQD</anno>)</c></seealso>.</p> + </item> </taglist> </desc> </func> @@ -5567,6 +5658,8 @@ 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 by the application @@ -6726,6 +6819,7 @@ ok <name name="system_info" arity="1" clause_i="65"/> <name name="system_info" arity="1" clause_i="66"/> <name name="system_info" arity="1" clause_i="67"/> + <name name="system_info" arity="1" clause_i="68"/> <fsummary>Information about the system.</fsummary> <desc> <p>Returns various information about the current system @@ -7131,7 +7225,17 @@ ok used by the runtime system. It is on the form "<major ver>.<minor ver>".</p> </item> - <tag><c>otp_release</c></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>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> <marker id="system_info_otp_release"></marker> <p>Returns a string containing the OTP release number of the |