number of clients queued by server and if a client is queued or not

Question

How to check if a client is backlogged by server ? and check how many clients are backlogged?

i have a server with SocketServer initialized and i have a client trying to connect. the server side code would be

  ServerSocket sock = new ServerSocket(9000,1);
  Socket so=sock.accept();

and the client side will be

  Socket soc = new Socket("localhost",9000);

Answer 1

How to check if a client is backlogged by server?

With a Selector.

and check how many clients are backlogged?

With Selector.selectedKeySet().size().

This assumes you are only selecting for OP_ACCEPT of course.