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Help me in chat application !

Posted on 2006-07-19
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Last Modified: 2010-04-05
I used indy TCP to make chat application both in client and server.

after a time (about 3 hours upper), CPU of server.exe near 100%, make my system LAG

I know function sleep() can solve this problem but I dont know where to put function sleep in.
 
in client code or in server code,

or is there a better way for server.exe than use sleep ?

please help me in detail.

thank all experts.

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Question by:lhquang
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Expert Comment

by:ciuly
Comment Utility
you will put a sleep(1) tipically or other small value in  loopes that take "forever" without doing anything. like

while not terminated do
  slee(100);

it is also advisable that you put application.processmessages; calls in such repetitive structures.
also, when doing client-server applications, you must use threads at least on teh server side to habdle client connections.
there are also other general issues that can cause a cpu eating up 100%.

so better post the code here so we can see exactly where those issues are. (maybe sleep is not the answer ;) )
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Wim ten Brink earned 500 total points
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I don't think Sleep() will solve this problem. All sleep does is halt the current thread and give another thread some CPU time. In general you would use Sleep(0) and not Sleep(1) if you just want another thread to start processing a bit more. (A Sleep(1) would add a delay of one millisecond, which might slow down your app considerably if you execute it often enough.)

The question is of course why your system needs so much CPU time. Maybe you're running out of memory because of a memory leak. Then it would be swapping to the swapfile. Or maybe something else is going wrong. Are you testing on multiple computers, where one is running the server and the other the client(s)? If so, which computer gets the 100% CPU?

It could also be that your application is calling Application.ProcessMessages or Sleep() too often. But I don't think Sleep() will solve it.

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Expert Comment

by:TheRealLoki
Comment Utility
the server runs its' clent connections inside a thread, so you do not need sleep
I would look for the problem elsewhere
can you post some of your code, and we might be able to spot the real problem
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Expert Comment

by:Scay7
Comment Utility
Have to agree here with TheRealLoki, we do not have enough information to help you. Also as Loki said its not a thread problem more likely a source twitch...
So paste you code where you think it use the most CPU time...

Peace Scay7
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Author Comment

by:lhquang
Comment Utility
the source code I developed from the chat demo in INDY 9. thank experts
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Expert Comment

by:TheRealLoki
Comment Utility
The Indy 9 chat demo is very buggy
firstly, the client can lock up on the
Msg := IdTCPClient1.ReadLn('', 5);
line in the Timer1Timer() event

This can be resolved by putting a TIdAntiFreeze on the form, but you still get a memory leak
(just watch the task maanger while your client is connected)
To resolve this you need to disable the TTimer while doing the ReadLn, so your Timer1Timer routine ends up looking something like this :-

procedure TForm1.Timer1Timer(Sender: TObject);
var
  Com,
  Msg : String;
begin
  if not IdTcpClient1.Connected then
    exit;
  Timer1.Enabled := False;
  try
    Msg := IdTCPClient1.ReadLn('', 5);

    if Msg <> '' then
      if Msg[1] <> '@' then
        begin
        { Not a system command }
          memLines.Lines.Add(Msg);
        end
      else
        begin
        { System command }
          Com := UpperCase(Trim(Copy(Msg, 2, Pos(':', Msg) -2)));
          Msg := UpperCase(Trim(Copy(Msg, Pos(':', Msg) +1, Length(Msg))));
          if Com = 'CLIENTS' then
            lbClients.Items.CommaText := Msg;
        end;
    finally
      Timer1.Enabled := True;
    end;
  end;

anyway, this may be the cause of your problems...
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Author Comment

by:lhquang
Comment Utility
anyone can give me the better demo than INDY DEMO ?
thanks
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Author Comment

by:lhquang
Comment Utility
oh, now I found out the my problem and fixed it.

thank everybody
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Expert Comment

by:Wim ten Brink
Comment Utility
Am just curious... What was the error exactly? :-)
Which reminds me... memlines.lines.add just keeps adding strings to a memo field. Does it also clean up this memo a bit? If not, lots of memory usage there...
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Author Comment

by:lhquang
Comment Utility
Workshop_Alex , u r right, memlines.lines.add just keeps adding strings to a memo field and I solved it
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