multithreading with non-blocking sockets

Question

I am trying to implement a TCP Server in Java using nio. Its simply using the Selector's select method to get the ready keys. And then processing those keys if they are acceptable, readable and so. Server is working just fine till im using a single thread. But when im trying to use more threads to process the keys, the server's response gets slowed and eventually stops responding, say after 4-5 requests. This is all what im doing:(Pseudo)

Iterator<SelectionKey> keyIterator =  selector.selectedKeys().iterator();
while (keyIterator.hasNext()) {
                SelectionKey readyKey = keyIterator.next();
                if (readyKey.isAcceptable()) {
                    //A new connection attempt, registering socket channel with selector

                } else {
                    Worker.add( readyKey );
                }

Worker is the thread class that performs Input/Output from the channel. This is the code of my Worker class:

private static List<SelectionKey> keyPool = Collections.synchronizedList(new LinkedList());

public static void add(SelectionKey key) {
    synchronized (keyPool) {
        keyPool.add(key);
        keyPool.notifyAll();
    }
}


public void run() {
    while ( true ) {

        SelectionKey myKey = null;
        synchronized (keyPool) {
            try {
                while (keyPool.isEmpty()) {
                    keyPool.wait();
                }
            } catch (InterruptedException ex) {                    
            }
            myKey = keyPool.remove(0);
            keyPool.notifyAll();
        }

        if (myKey != null && myKey.isValid() ) {

            if (myKey.isReadable()) {
                //Performing reading
            } else if (myKey.isWritable()) {
                //performing writing
                myKey.cancel();  
            }
        }
    }

My basic idea is to add the key to the keyPool from which various threads can get a key, one at a time. My BaseServer class itself is running as a thread. It is creating 10 Worker threads before the event loop to begin. I also tried to increase the priority of BaseServer thread, so that it gets more chance to accept the acceptable keys. Still, to it stops responding after approx 8 requests. Please help, were I am going wrong. Thanks in advance. :)

Answer 1

Third, you aren't removing anything from the selected-key set. You must do that every time around the loop, e.g. by calling keyIterator.remove() after you call next().

You need to read the NIO Tutorials.