[erlang-questions] Erlang proccess memory usage

[Chris Hicks]

The first problem you are running into is that you are mistaking "words" for "bytes" see: http://www.erlang.org/doc/efficiency_guide/advanced.html

With that information in mind this is what you are really looking at for 1M processes:

From: wsong.cn@REDACTED
Date: Tue, 10 May 2011 11:55:04 +0800
To: erlang-questions@REDACTED
Subject: Re: [erlang-questions] Erlang proccess memory usage

Also I tried to use proc_lib:hibernate/3 with no difference.

On Tue, May 10, 2011 at 11:50 AM, Wenqiang Song <wsong.cn@REDACTED> wrote:


Hi, 

I'm experimenting with Erlang process and found something that not expected. 
What I do is creating 1M Erlang processes and measure memory usage. Code is as follow:


-module(generator).-export([start/0, generator/2, loop/0]).
start() ->    Pid = self(),    spawn( fun()->generator(19,Pid) end ),    count (1).



count (Num) ->    receive	add ->%	    io:format("Oopss, ~n"),


	    if 		0 =:= ( Num rem 10000 ) -> io:format("Count ~p~n", [Num]);
		true -> Q = 3	    end,	    count (Num + 1);
	_ ->	    io:format("haha, ~n")    after 30000 ->
	    io:format("Count ~p~n", [Num]),	    count (Num)    end.
loop() ->    receive	_ ->	    io:format("Oops ~n"),
%	    proc_lib:hibernate(?MODULE, loop(), [])	    loop()    end.
generator( 0, Pid ) ->    Pid ! add,%    proc_lib:hibernate(?MODULE, loop(), []);    loop();generator( Depth, Pid ) ->    spawn( fun()->generator(Depth - 1, Pid) end),


    spawn( fun()->generator(Depth - 1, Pid) end),    Pid ! add,%    io:format("Depth: ~p, pid: ~p~n", [Depth, Pid]),%    proc_lib:hibernate(?MODULE, loop(), []).


    loop().===============End of Code=============2> i(0,58,0).[{current_function,{generator,loop,0}}, {initial_call,{erlang,apply,2}}, {status,waiting},


 {message_queue_len,0}, {messages,[]}, {links,[]}, {dictionary,[]}, {trap_exit,false}, {error_handler,error_handler}, {priority,normal}, {group_leader,<0.25.0>},


 {total_heap_size,233}, {heap_size,233}, {stack_size,1}, {reductions,9}, {garbage_collection,[{min_bin_vheap_size,46368},                      {min_heap_size,233},


                      {fullsweep_after,65535},                      {minor_gcs,0}]}, {suspending,[]}]
3> memory().[{total,2759895784},


 {processes,2751081712}, {processes_used,2751067504}, {system,8814072}, {atom,615121}, {atom_used,589205}, {binary,8608}, {code,5845747}, {ets,270928}]



Total memory usage is about 2.7G. While when I use i() and i(pid) I saw that each process only uses about 233 bytes. I can't find where the memory is used. Any idea?



ThanksAndy


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