I'm trying to limit the number of connections my server will accept using semaphores, but when running, my code doesn't seem to make this restriction - am I using the semaphore correctly? eg. I have hardcoded the number of permit as 2, but I can connect an unlimited number of clients...

public class EServer implements Runnable {
    private ServerSocket serverSocket;
    private int numberofConnections = 0;
    private Semaphore sem = new Semaphore(2);
    private volatile boolean keepProcessing = true;

    public EServer(int port)
            throws IOException {
        serverSocket = new ServerSocket(port);
    }

    @Override
    public void run() {
        while (keepProcessing) {
            try {
                sem.acquire();
                Socket socket = serverSocket.accept();
                process(socket, getNextConnectionNumber());
            } catch (Exception e) {
            } finally {
                sem.release();
            }
        }
        closeIgnoringException(serverSocket);
    }

    private synchronized int getNextConnectionNumber() {
        return ++numberofConnections;
    }

    // processing related methods
}