[erlang-questions] How about the net IO ability of erlang

Rapsey <>
Wed Sep 10 14:06:56 CEST 2008


gen_tcp:send is a very expensive call. Try to buffer the data for a bit
before sending it. I use 8kB and have filled up a 500mbit connection without
problems.
When I had small packets (< 1k) CPU usage was very high.


Sergej

2008/9/10 leon zhao <>

> I worte a tcp proxy to forward data from peer to peer, but i find the CPU
> usage of beam is high in test
> The client make 1000 connections per second and get 16K data from
> server, and the server send 8K to client per second, because we want to
> decrease the traffic.
> And the compute's CPU is Intel(R) Xeon(TM) CPU 3.20GHz, so the proxy's
> usage is on avenage 26%
> Is my codes have some problem or erlang need some optimization.
> Anyone can tell me
>
> here is my codes
>
> %%%----------------------------------------------------------------------
> %%% File    : tcp.erl
> %%% Author  : Zhao Liang<>
> %%%----------------------------------------------------------------------
> -module(tcp).
> -author('' <%%27>).
> -compile(export_all).
>
> -define(MAIN_MODULE,  tcp).
>
> -record(cfg, {
>  listen_port = 10080,
>  idle = 30000}).
>
> main(Port) ->
>     Cfg = #cfg{listen_port=Port},
>     case gen_tcp:listen(Port, [{reuseaddr,true}, {active,false},
> {backlog,64}, binary]) of
>         {ok, LSock} ->
>             create_accept_thread(LSock, Cfg, self()),
>             tcp_ctl_loop(LSock, Cfg, self());
>         ERR -> ERR
>     end.
> tcp_ctl_loop(LSock, Cfg, Self) ->
>     receive
>     {_, next} ->
>         create_accept_thread(LSock, Cfg, Self),
>         tcp_ctl_loop(LSock, Cfg, Self);
>     _ ->
>         tcp_ctl_loop(LSock, Cfg, Self)
>     end.
> create_accept_thread(LSock, Cfg, Pid) ->
>     spawn_link(?MAIN_MODULE, accept_thread, [LSock, Cfg, Pid]).
> accept_thread(LSock, Cfg, Parent) ->
>     accept_loop(LSock, Cfg, Parent).
> accept_loop(LSock, Cfg, Parent) ->
>     case prim_inet:async_accept(LSock, -1) of
>         {ok, Ref} ->
>             receive
>                 {inet_async, LSock, Ref, {ok,CSock}} ->
>                     Parent ! {self(), next},
>                     tcp_start(CSock, Cfg);
>                 {inet_async, LSock, Ref, _} ->
>                     accept_loop(LSock, Cfg, Parent)
>             end;
>         _ ->
>             accept_loop(LSock, Cfg, Parent)
>     end.
> tcp_start(CSock, Cfg) ->
>     case prim_inet:getopts(CSock, [original_dst]) of
>         {ok, [{original_dst, {Oport, Oip}}]} ->
>             case gen_tcp:connect(Oip, Oport, [{active,true}, {packet,raw},
> binary], Cfg#cfg.idle) of
>                 {ok, SSock} ->
>                     tcp_start(CSock, SSock, Cfg);
>                 _ ->
>                     inet:tcp_close(CSock)
>             end;
>         _ ->
>             inet:tcp_close(CSock)
>     end.
> tcp_start(CSock, SSock, Cfg) ->
>     inet:setopts(CSock, [{active, true}, {packet,raw}, binary]),
>     tcp_data_loop(CSock, SSock, Cfg).
> tcp_data_loop(CSock, SSock, Cfg) ->
>     receive
>         {tcp, Socket, Data} ->
>             if
>                 Socket == CSock ->
>                     case prim_inet:send(SSock, Data) of
>                         ok ->
>                             tcp_data_loop(CSock, SSock, Cfg);
>                         _ ->
>                             gen_tcp:close(CSock),
>                             gen_tcp:close(SSock)
>                     end;
>                 Socket == SSock ->
>                     case prim_inet:send(CSock, Data) of
>                         ok ->
>                             tcp_data_loop(CSock, SSock, Cfg);
>                         _ ->
>                             gen_tcp:close(CSock),
>                             gen_tcp:close(SSock)
>                     end;
>                 true ->
>                     tcp_data_loop(CSock, SSock, Cfg)
>             end;
>         {tcp_closed, Socket} ->
>             if
>                 Socket == CSock ->
>                     gen_tcp:close(SSock);
>                 Socket == SSock ->
>                     gen_tcp:close(CSock);
>                 true ->
>                     gen_tcp:close(CSock),
>                     gen_tcp:close(SSock)
>             end;
>          _ ->
>             gen_tcp:close(CSock),
>             gen_tcp:close(SSock)
>     after
>         Cfg#cfg.idle ->
>             gen_tcp:close(CSock),
>             gen_tcp:close(SSock)
>     end.
>
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> 
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