Java server sockets disconnect after some time

Question

I have written a server that creates the threads and opens the sockets. The client is written in Flash. The server is not responding anymore to clients after some time.

The server:

public appGameServer(String Ip){
  try{
      _SS = new ServerSocket(appMain.CONFIG_GAME_PORT);
      _SS.setSoTimeout(0);
      _startTime = System.currentTimeMillis();
      _gameServerThread = new Thread(this);
      _gameServerThread.start();
      try{
          _startFunctions();
       }
       catch (Exception e) {
          e.printStackTrace();
          Debug.err.println(e.getMessage());
      }
  } catch (IOException e) {
      Debug.err.println("Could not listen on port " + appMain.CONFIG_GAME_PORT);
      e.printStackTrace();
         System.exit(0);
    }
}

public void _startFunctions(){
    actiuniGlobale.schedule(new TimerTask(){
        public void run(){
        }
    }, 0,500);
}
@Override
public void run(){ 
    while(appMain.isRunning) {
        try {
            _clients.add(new appMainSystem(_SS.accept()));
            _jucatoriOnline = _clients.size();
        }catch(IOException e){
            e.printStackTrace();
            Debug.err.println(e.getMessage());
        }
    }
}

public static void delClient(appMainSystem serverPrincipal) {
    try{
        synchronized (_clients){
            _clients.remove(serverPrincipal);
            _jucatoriOnline = _clients.size();
        }
    }catch(Exception e){
        e.printStackTrace();
       Debug.err.println(e.getMessage());
    }
}

public static void kickAll()
{
    try {
        _SS.close();
    } catch (IOException e) {}

    List<appMainSystem> c = Collections.synchronizedList(new ArrayList<appMainSystem>());
    c.addAll(_clients);
    for(appMainSystem GT : c) {
        try {
             GT.closeSocket();
        } catch(Exception e) {           
            e.printStackTrace();
            Debug.err.println(e.getMessage());};  
    }
}

The packet handler:

public appMainSystem(Socket sock) {
    try{
        _s = sock;
        _s.setSoTimeout(0);
        _in = new BufferedReader(new InputStreamReader(_s.getInputStream()));
        _out = new PrintWriter(_s.getOutputStream(),true);
        try{
            _t = new Thread(this);
            _t.setDaemon(true);
            _t.start();
        }
        catch (Exception e) {
            Debug.err.println(e.getMessage());
            e.printStackTrace();
        }
    }
    catch (IOException e) {
        Debug.err.println(e.getMessage());
        e.printStackTrace();
        if(!_s.isClosed()){
            try{
                _s.close();
            } catch (IOException e1) {Debug.err.println(e1.getMessage());e1.printStackTrace();}
        }
    }
}

public void run(){
    try{
        String packet = "";
        char charCur[] = new char[1];
        while(_in.read(charCur)!=-1 && appMain.isRunning)  {
            if (charCur[0] != '\u0000' && charCur[0] != '\n' && charCur[0] != '\r') {
                packet += charCur[0];
            } else if(!packet.isEmpty()) {
                packet = new String(packet.getBytes(),"UTF8");
                try {
                    verificaPacket(packet);
                } catch(Exception e) {
                    Debug.err.println(e.getMessage());
                    e.printStackTrace();
                }
                packet = "";
            }
        }
    }catch(Exception e) {
        kick();
    }
    finally
    {
        if(!lastPacketRecv.isEmpty()) kick();
    }
}   
public void kick()
{
    try{
        appGameServer.delClient(this);
        closeSockets();
    } catch(Exception e){
        Debug.err.println(e.getMessage());
        e.printStackTrace();
    }
}

public void closeSockets() throws IOException {
    _in.close();
    _out.close();
    if(!_s.isClosed()) closeSocket();
    _t.interrupt();
} 

public void closeSocket()
{
    try {
        _s.close();
    } catch (IOException e) {           
        Debug.err.println(e.getMessage());
        e.printStackTrace();
    }
}

What do you mean by "no responding"? Is there some kind of error client side or server side? Maybe exhausted resources (threads remaining alive, or sockets not being closed?) — Alkis Kalogeris, Dec 24 '13 at 18:13
The main server thread work, he is dooing an job in one of that timers only the connection don't work. There is no resource problem and the threads as i can see in debuger are closing corectly. You guys see any mistake in my code? — Şήøωў, Dec 24 '13 at 18:25
Wait. What do you mean by "The main server thread work, he is dooing an job in one of that timers"? The main server thread must only listen for connection and create thread childs and assign them the connection. NOTHING else, or the server will appear busy (as it does). — Alkis Kalogeris, Dec 24 '13 at 18:27
Editing your question out is not appropriate. We do not delete content just because you got your answer. — Andrew Barber, Dec 25 '13 at 21:10

score 1 · Accepted Answer · answered Dec 24 '13 at 18:26

I can't tell from your code if this advice is applicable, but threads that read or write from sockets should do NOTHING else. Read threads should queue their data, and write threads should be fed from a data queue. Reading and writing should be done in different threads.

Otherwise, the unpredictability of buffering and actual data transmission guarantees that unexpected stall conditions will occur.

Java server sockets disconnect after some time

The server:

1 Answers1