Does SelectableChannel.register block until Selector.select completes

Question

Hey all,
Quick question. If I have 2 threads and I am trying to register a SocketChannel with a selector from one, and the other is currently in a selection operation. Does the registering operation block until the select operation finishes?
i.e. The below appears to block indefinitely. Is this behavior avoidable, or do I need to force a selector wake-up to finish registering?
public class RegisterLock {
     * @param args
    public static void main(String[] args) throws Exception {
        ServerSocketBinder binder = new ServerSocketBinder(false);
        final ServerSocket server = binder.acquireServerSocket();
        final ServerSocketChannel serverSocket = binder.acquireServerSocketChannel();
        serverSocket.configureBlocking(false);
        final Selector sel = Selector.open();
        serverSocket.register(sel, SelectionKey.OP_ACCEPT);
        Thread t = new Thread(new Runnable() {
            public void run() {
                try {
                    Thread.sleep(5000);
                } catch (InterruptedException e) { }
                try {
                    SocketChannel socket = SocketChannel.open();
                    socket.configureBlocking(false);
                    socket.connect(new InetSocketAddress(server.getInetAddress(), server.getLocalPort()));
                    System.out.println("Registering socket with selector...");
                    socket.register(sel, SelectionKey.OP_CONNECT);
                    System.out.println("Successfully registered socket with selector.");
                    System.exit(0);
                } catch (IOException e) { }
        t.start();
        System.out.println("Beginning select operation");
        sel.select();
}

Answer 1

Yes. Both operations synchronize on the same data structure. There are three answers:
(a) selector.wakeup() before registering. Ensure your select() loop copes correctly with a selection result of zero, i.e. just does background operations and continues, doesn't treat it as a failure
(b) Use a short selection timeout. Same remarks apply
(c) use a queue of pending registrations and do all registration operations in the select() loop/thread.