[erlang-questions] help about process,why very slow.

Sean Hinde <>
Sun Feb 17 14:19:18 CET 2008


Hi,

Why do you think the CPU should be anything other than 100% when you  
have just sent 1000000 messages into the system. It is of course busy  
processing the messages.

Sean

On 17 Feb 2008, at 13:03, 瞄瞄 wrote:

> hi!
> I checked the server found in erlang shell activated when launched  
> smp, my server is single core, smp cancelled after the running of  
> the entire service soon, but still high cpu occupiers, the test data  
> will be 1000000 continuing seconds cpu 99% usage, may I ask you what  
> optimization approach? Cpu occupiers will be reduced?
>
> thanks All!
>
> 2008/2/17 myname iserl <>:
> Hi,
>
> Sorry, for offlist.
> I don't use erlang yet and I don't really know erlang at all,
> but I read the list often.
>
> For monitoring why your server is using 99% you might try:
> http://www.erlang.org/documentation/doc-5.2/lib/observer-0.9/doc/html/etop_ug.html
> http://www.erlang.org/doc/efficiency_guide/profiling.html
>
> http://www.erlang.org/doc/man/eprof.html
> http://www.erlang.org/doc/man/fprof.html
> http://www.erlang.org/doc/apps/tools/cprof_chapter.html
>
> Good luck
>
> 瞄瞄 wrote:
> > thanks!
> > I was revised to {active,once} and server cpu still occupy 99%,  
> but my
> > code in the local tests, use  127.0.0.1 <http://127.0.0.1/>,100  
> million
> > run by 40 seconds, and even in the server 127.0.0.1 <http://127.0.0.1/ 
> >
> > of the cpu will be 99%.
> >
> > Is there any way to find out whether there is a server cpu 99%?
> >
> > very thanks!
> >
> > 2008/2/16 Sean Hinde < <mailto: 
> >>:
> >
> >     The problem here is almost certainly your use of {active,  
> true}. The
> >     inbound mailbox will rapidly fill with a very large number of  
> messages
> >     (1 million in your case), and this can cause the emulator to  
> slow down
> >     during garbage collection.
> >
> >     You need to introduce some flow control. The {active,once}  
> socket
> >     option is normally used for this.
> >
> >     Sean
> >
> >     On 16 Feb 2008, at 12:18, 瞄瞄 wrote:
> >
> >      > help!
> >      >
> >      > On Feb 16, 2008 11:32 AM, 瞄瞄 <
> >     <mailto:>> wrote:
> >      > server code url
> >      > http://icej.80s.net.cn/emssserver.erl
> >      >
> >      > On Sat, Feb 16, 2008 at 11:26 AM, 瞄瞄 <
> >     <mailto:>> wrote:
> >      >
> >      > Hello everyone! I recent study erlang familiar with the  
> code to
> >     make a
> >      > message transmitted server, have a problem!
> >      >
> >      > I development of the information transmitted server function:
> >      > Aclient Bclient are connected to Server, and joined a group  
> C,
> >     Aclient
> >      > send message to group C , message will be transmitted to B by
> >     group C.
> >      > SOCKET use the binary (active true), (2) packet.
> >      >
> >      > News Server design:
> >      > Have a process responsible for monitoring all client even  
> when the
> >      > client connect server, another process (group_manager  
> process)
> >      > maintenance division List of members of the client group,  
> each group
> >      > (group process) to have an process within the group  
> responsible for
> >      > the
> >      > client to transmit message.
> >      >
> >      >
> >      > Performance testing problems encountered by:
> >      > A test of million sent to the SERVER message used on the  
> finished
> >      > eight
> >      > seconds, and automatic logoff, and the content of the  
> message are the
> >      > same, so, the test Lan network.
> >      > SERVER through tcpdump monitor and indeed also in the eight  
> seconds
> >      > are
> >      > all the message at the end, and not from the message into  
> the A,
> >      > however
> >      > SERVER transmitted to the messages with for a very long  
> time, over 10
> >      > minutes, finally, I end of the process.
> >      >
> >      > In server,use top,the cpu is 99% by beam.smp.
> >      > PID USER PR NI VIRT RES SHR S %CPU %MEM TIME+ COMMAND
> >      > 31586 root 17 0 70564 18m 1868 S 99.9 0.9 15:46.12 beam.smp
> >      >
> >      > Is it a problem I designed a very slow ? Or as a result of  
> the
> >     process
> >      > of communication? What measures can be taken tuning?
> >      >
> >      > Thank you help!
> >      >
> >      > the server code
> >      > # -module(emssserver).
> >      > # -export([init/0]).
> >      > # -define(TCP_OPTIONS,[binary,{packet, 2}, {active, true},
> >     {reuseaddr,
> >      > true}]).
> >      > # -define(PORT,7000).
> >      > # -define(Debug,"YES").
> >      > #
> >      > # -ifdef(Debug).
> >      > # -define(DEBUG(Fmt, Args), io:format(Fmt, Args)).
> >      > # -else.
> >      > # -define(DEBUG(Fmt, Args), no_debug).
> >      > # -endif.
> >      > # -record(group,{name,gpid}).
> >      > # -record(client, {name,pid,socket}).
> >      > #
> >      > # init()->
> >      > # {ok, Listen} = gen_tcp:listen(?PORT, ?TCP_OPTIONS),
> >      > # register(accept_connection, spawn(fun() ->
> >     accept_connection(Listen)
> >      > end)),
> >      > # register(group_manage, spawn(fun() -> group_manage([])  
> end)).
> >      > #
> >      > # accept_connection(Listen) ->%% listen new client connection
> >      > # {ok, Socket} = gen_tcp:accept(Listen),
> >      > # Pid = spawn(fun() -> client_recv(Socket,"","") end),
> >      > # gen_tcp:controlling_process(Socket,Pid),
> >      > # accept_connection(Listen).
> >      > #
> >      > # client_recv(Socket,ClientName,GroupPid)->%%client process  
> recv
> >      > # receive
> >      > # {tcp, Socket, Bin} ->
> >      > # ?DEBUG("Server recv Data\r\n",""),
> >      > # case binary_to_term(Bin) of
> >      > # {join,JoinName,ClientNameTmp}->%%client join
> >      > # ?DEBUG("client_recv Join:~s ~s\r\n", 
> [JoinName,ClientNameTmp]),
> >      > # G=#group{name=JoinName},
> >      > # group_manage ! {join,G,self()},%%get group pid
> >      > # receive
> >      > # {grouppid,GPid}->%%recv group pid
> >      > # ?DEBUG("Client_recv grouppid ~w ~s\r\n", 
> [GPid,ClientNameTmp]),
> >      > # GPid!{join,Socket,ClientNameTmp,self()} %% send "join"  
> msg to group
> >      > # end,
> >      > # client_recv(Socket,ClientNameTmp,GPid);
> >      > # {send,GroupName,Msg}->%%send msg to group
> >      > # ?DEBUG("client_recv Send:~s ~s\r\n",[GroupName,Msg]),
> >      > # GroupPid!{send,ClientName,Msg},
> >      > # client_recv(Socket,ClientName,GroupPid)
> >      > # end;
> >      > # {tcp_closed, Socket} ->
> >      > # ?DEBUG("client_recv close\r\n",[])
> >      > # end.
> >      > #
> >      > # group_manage(Group)->%%manage group member
> >      > # ?DEBUG("group_manage start\r\n",[]),
> >      > # receive
> >      > # {join,JoinGroup,ClientPid}->
> >      > # ?DEBUG("group_manage Join:~s\r\n",[JoinGroup#group.name]),
> >      > # case lists:keysearch(JoinGroup#group.name, #group.name,  
> Group) of
> >      > # false ->
> >      > # Pid=spawn(fun() -> group([]) end),
> >      > # ?DEBUG("group_manage group pid~w\r\n",[Pid]),
> >      > # ClientPid!{grouppid,Pid},%%return client_recv group pid
> >      > # JoinGroupp = #group{name=JoinGroup#group.name,gpid=Pid},
> >      > # Gs = [JoinGroupp|Group],
> >      > # ?DEBUG("group_manage group:~w\r\n",[Gs]),
> >      > # group_manage(Gs);
> >      > # {value,SingleGroup} ->
> >      > # ?DEBUG("group_manage group is set
> >     ~s\r\n",[SingleGroup#group.name]),
> >      > # ClientPid!{grouppid,SingleGroup#group.gpid},
> >      > # group_manage(Group)
> >      > # end
> >      > #
> >      > # end.
> >      > #
> >      > # group(Client)->%%send msg to all
> >      > # ?DEBUG("group \r\n",[]),
> >      > # receive
> >      > # {join,Socket,ClientName,CPid} ->
> >      > # ?DEBUG("group ClientName ~s\r\n",[ClientName]),
> >      > # ?DEBUG("group Client set ~w\r\n",[Client]),
> >      > # case lists:keysearch(ClientName,#client.name,Client) of
> >      > # false->
> >      > # ?DEBUG("group new client\r\n",[]),
> >      > # ClientNew =  
> #client{name=ClientName,pid=CPid,socket=Socket},
> >      > # ClientTmp = [ClientNew|Client],
> >      > # group(ClientTmp);
> >      > # {value,SingleClient}->
> >      > # ?DEBUG("group client is set ~s\r\n", 
> [SingleClient#client.name]),
> >      > # group(Client)
> >      > # end;
> >      > # {send,ClientName,Msg}->
> >      > # ?DEBUG("group recv client send ~s\r\n",[Msg]),
> >      > # lists:foreach(fun(T)->send(ClientName,T,Msg) end,Client),
> >      > # group(Client)
> >      > # end,
> >      > # ok.
> >      > #
> >      > # send(FClientName,TClientName,Msg)->
> >      > # if
> >      > # FClientName /= TClientName#client.name ->
> >      > # ?DEBUG("send f:~s t:~s
> >      > ~s\r\n",[FClientName,TClientName#client.name,Msg]),
> >      > # M = {FClientName,Msg},
> >      > # gen_tcp:send(TClientName#client.socket,term_to_binary(M));
> >      > # true->
> >      > # ?DEBUG("send from eq to\r\n",[])
> >      > # end.
> >      >
> >      > the client code is "gen_tcp:send",iterative
> >      >
> >      > the code install three linux server.
> >      >
> >      >
> >      >
> >      >
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