multiple clients with server handling

Question

I am just starting to learn sockets and client/servers. I am not clear on the following concept. Assume non-blocking sockets.

Assume I have a server application, and I have 1000 clients trying to talk to it, I think it is very realistic. Assume the client and server talk via sockets. 1- Does this mean that with every client, there is a separate socket connection? (Do we have 1000 sockets, or one socket with 1000 connections?

2- Does every socket connection belong to a separate thread? If Yes, How can we limit number of threads as it can get out of control?

Answer 1

Assuming you're using TCP, then every connection is over a separate socket. The operating system allocates them using file descriptors.

When using a protocol like UDP, this need not be the case, and won't be unless you write the code to do make it happen.

Threading? It depends on how you build the server. You don't need threads to be a part of a server at all and you can (obviously) have multiple threads with just a single connection. One common way of doing things, however, is to hand the socket returned by accept() to a new thread, yes.

If you don't have an interest in threads--for example, if the server only performs very quick tasks and creating a thread is just wasting time--you can use select() to poll the sockets and determine which ones need attention. Some servers use a combination of threading and polling to try to maximize throughput.