Question

i am trying to build a multi threaded server that is supposed to spawn new threads for every incoming connection, BUT for all my effort, it spawns new threads only when it feels like it, Can anybody help me debug this code? am i missing something obvious?

 while (true)
 {
   if (txtAddress.Text.Trim() == "Any" || txtAddress.Text.Trim() == "any")
      ipEndP = new IPEndPoint(IPAddress.Any, 778);
   else
      ipEndP = new IPEndPoint(IPAddress.Parse(txtAddress.Text.Trim()), 778);

      tcpL = new TcpListener(ipEndP);
      tcpL.Server.SetSocketOption(SocketOptionLevel.Socket, SocketOptionName.ReuseAddress, true);

      tcpL.Start();
      tempSock = tcpL.AcceptSocket();

 //t = new Thread(ConnectionHandler); //When new client is connected, new thread       //is created to handle the connection
 //t.Priority = ThreadPriority.Highest;
 //t.Start(tempSock);

 ThreadPool.QueueUserWorkItem(ConnectionHandler, tempSock);
 }

Answer 1

Check out the MSDN docs for QueueUserWorkItem

Queues a method for execution. The method executes when a thread pool thread becomes available.

Placing a thread in the user work item queue does not guarantee that it will begin executing right away. That’s actually a good thing. If you got so many connections that you needed hundreds or thousands of threads, that could easily bring your server to it’s knees (and certainly would be very wasteful due to excessive context switches).

Your commented out code should kick off a new thread for every connection. Is that not working? If so, what exactly is not working? Note that creating a new thread for every connection is much more expensive than using the thread pool.

UPDATE

Based on your remark that the commented out code is also failing to create too many threads, I would add…

You are creating WAY too many threads if that happens.

Often I see people asking why they can’t create more than around 2000 threads in a process. The reason is not that there is any particular limit inherent in Windows. Rather, the programmer failed to take into account the amount of address space each thread uses.

A thread consists of some memory in kernel mode (kernel stacks and object management), some memory in user mode (the thread environment block, thread-local storage, that sort of thing), plus its stack. (Or stacks if you’re on an Itanium system.)

Usually, the limiting factor is the stack size.

http://blogs.msdn.com/b/oldnewthing/archive/2005/07/29/444912.aspx