From 3ac08f9b668613a4292436979eacc61863c2ab94 Mon Sep 17 00:00:00 2001 From: Rickard Green Date: Wed, 16 Sep 2015 15:02:50 +0200 Subject: Fragmented young heap generation and off_heap_message_queue option * The youngest generation of the heap can now consist of multiple blocks. Heap fragments and message fragments are added to the youngest generation when needed without triggering a GC. After a GC the youngest generation is contained in one single block. * The off_heap_message_queue process flag has been added. When enabled all message data in the queue is kept off heap. When a message is selected from the queue, the message fragment (or heap fragment) containing the actual message is attached to the youngest generation. Messages stored off heap is not part of GC. --- erts/doc/src/erlang.xml | 77 +++++++++++++++++++++++++++++++++++++++++++++++-- 1 file changed, 75 insertions(+), 2 deletions(-) (limited to 'erts/doc/src/erlang.xml') diff --git a/erts/doc/src/erlang.xml b/erts/doc/src/erlang.xml index e77532463e..9426d30390 100644 --- a/erts/doc/src/erlang.xml +++ b/erts/doc/src/erlang.xml @@ -4058,8 +4058,46 @@ os_prompt% process.

Returns the old value of the flag.

+ + Set process flag off_heap_message_queue for the calling process + +

This flag determines how messages in the message queue + are stored. When the flag is:

+ + true +

+ All messages in the message queue will be stored + outside of the process heap. This implies that no + messages in the message queue will be part of a garbage + collection of the process. +

+ false +

+ Messages may be placed either on the heap or outside + of the heap. +

+ +

+ If the process potentially may get a hugh amount of messages, + you are recommended to set the flag to true. 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 false. +

+

+ When changing this flag from false to true, + all messages in the message queue are moved off heap. This + work has been initiated but not completed when this function + call returns. +

+

Returns the old value of the flag.

+ + + + Set process flag priority for the calling process @@ -4138,7 +4176,7 @@ os_prompt% - + Set process flag save_calls for the calling process

N must be an integer in the interval 0..10000. @@ -4162,7 +4200,7 @@ os_prompt% - + Set process flag sensitive for the calling process

Set or clear the sensitive flag for the current process. @@ -4408,6 +4446,14 @@ os_prompt% monitor by name, the list item is {process, {RegName, Node}}.

+ {off_heap_message_queue, OHMQ} + +

Returns the current state of the off_heap_message_queue + process flag. OHMQ is either true, or + false. For more information, see the documentation of + process_flag(off_heap_message_queue, + OHMQ).

+ {priority, Level}

Level is the current priority level for @@ -5067,6 +5113,7 @@ true + Create a new process with a fun as entry point

Returns the pid of a new process started by the application @@ -5081,6 +5128,7 @@ true + Create a new process with a fun as entry point on a given node

Returns the pid of a new process started by the application @@ -5093,6 +5141,7 @@ true + Create a new process with a function as entry point

Works exactly like @@ -5188,6 +5237,18 @@ true fine-tuning an application and to measure the execution time with various VSize values.

 + {off_heap_message_queue, OHMQ} + +

Sets the state of the off_heap_message_queue process + flag. OHMQ should be either true, or + false. The default off_heap_message_queue process + flag is determined by the + +xohmq erl + command line argument. For more information, see the + documentation of + process_flag(off_heap_message_queue, + OHMQ).

+ @@ -5195,6 +5256,7 @@ true + Create a new process with a function as entry point on a given node

Returns the pid of a new process started by the application @@ -6224,6 +6286,7 @@ ok + Information about the system

Returns various information about the current system @@ -6614,6 +6677,16 @@ ok

Returns a string containing the erlang NIF version used by the runtime system. It will be on the form "<major ver>.<minor ver>".

+ off_heap_message_queue + +

Returns the default value of the off_heap_message_queue + process flag which is either true or false. This + default is set by the erl command line argument + +xohmq. For more information on the + off_heap_message_queue process flag, see documentation of + process_flag(off_heap_message_queue, + OHMQ).

+ otp_release

Returns a string containing the OTP release number of the -- cgit v1.2.3