My server gets stuck by Thread.sleep?

Question

I have this code executed as a thread for each client to detect the disconnection of an user in my server:

private void detectDisconnect (Client user)
{ 
    try  
    {
        boolean listening = true;

        while (listening)
        { 
            System.out.println("<" + user.getUserName() + "> Sleeping...");
            user.setDisconnected(true); 
            send(user, "heartBeat#"); 
            Thread.sleep(Main.LATENCY);
            System.out.println("<" + user.getUserName() + "> I wake up!");

            if (user.isDisconnected()) { listening= false; exitClient(user);                 
        }  
    } 
    catch (InterruptedException e) { e.printStackTrace(); }
}

The server before of sleeping put user.setDisconnected(true); and if the client send a response before of waking up I change to user.setDisconnected(false); in other method(), so this thread won't exit the Client unless in the latency's period doesn't get any message... This works fine, but sometimes randomly I could check that after the message of "Sleeping..." does not appear the message "I wake up!" (!!!), and the worst thing is that ALL MY PROGRAM GETS FROZEN, so the server doesn't listen or send messages to any client anymore :( even being these in separated Threads executing!....

I don't know why this happen, but I think that all the problems are caused by some eventually fatal error in Thread.sleep(). Could be possible? But I don't receiving any error message in the catch(Exception e){}, so I'm going crazy xD

Help please!!

What's he value of `Main.LATENCY` ? and the code of Thread.sleep() ? — Patrick Trentin, Mar 18 '16 at 11:49
protected final static int LATENCY = 10000; is latency the code of Thread.sleep() is the same of above — Andrés Fg, Mar 18 '16 at 11:53
`Thread.Sleep` is really really bad in this case. It hurts scalability. You're better off doing async calls. — mrahhal, Mar 18 '16 at 11:57
I would start by putting a more general `catch (Exception e)` there — Patrick Trentin, Mar 18 '16 at 12:00
private void send (Cliente user, String msg) { user.getWriterClient().println("general#" + msg); user.getWriterClient().flush(); } — Andrés Fg, Mar 18 '16 at 12:15
user.getWriterClient() is a new PrintWriter(new OutputStreamWriter(socketClient.getOutputStream(), "UTF-8"), true); — Andrés Fg, Mar 18 '16 at 12:17
Can you edit your question instead of adding code here in the comments? that's unclear. It seems to me these functions can throw exceptions, perhaps the problem is there. — Patrick Trentin, Mar 18 '16 at 12:21
That's it!! I will put a System.out.println between send() and sleep(), so that I will be able to know if the error comes from send or sleep. Thank you! — Andrés Fg, Mar 18 '16 at 12:30
Can't you just expand the `catch()` section? using `println` is just poor's man debugging... :) — Patrick Trentin, Mar 18 '16 at 12:35

My server gets stuck by Thread.sleep?

0 Answers0