It's not a question really, i'm just looking for some guidelines :) I'm currently writing some abstract tcp server which should use as low number of threads as it can.

Currently it works this way. I have a thread doing listening and some worker threads. Listener thread is just sits and wait for clients to connect I expect to have a single listener thread per server instance. Worker threads are doing all read/write/processing job on clients socket.

So my problem is in building efficient worker process. And I came to some problem I can't really solve yet. Worker code is something like that(code is really simple just to show a place where i have my problem):

List<Socket> readSockets = new List<Socket>();
List<Socket> writeSockets = new List<Socket>();
List<Socket> errorSockets = new List<Socket>();

while( true ){
    Socket.Select( readSockets, writeSockets, errorSockets, 10 );

    foreach( readSocket in readSockets ){
        // do reading here
    }

    foreach( writeSocket in writeSockets ){
        // do writing here
    }

    // POINT2 and here's the problem i will describe below 
}

it works all smothly accept for 100% CPU utilization because of while loop being cycling all over again, if I have my clients doing send->receive->disconnect routine it's not that painful, but if I try to keep alive doing send->receive->send->receive all over again it really eats up all CPU. So my first idea was to put a sleep there, I check if all sockets have their data send and then putting Thread.Sleep in POINT2 just for 10ms, but this 10ms later on produces a huge delay of that 10ms when I want to receive next command from client socket.. For example if I don't try to "keep alive" commands are being executed within 10-15ms and with keep alive it becomes worse by atleast 10ms :(

Maybe it's just a poor architecture? What can be done so my processor won't get 100% utilization and my server to react on something appear in client socket as soon as possible? Maybe somebody can point a good example of nonblocking server and architecture it should maintain?