C/Linux TCP Socket Server

Question

I'm implementing a TCP socket server in C and Linux. It will be a chat server handling many requests simultaneously. Here is the pseudo code for how it is setup

create a socket
bind to a well-known port
use listen to place in passive mode
while (1)
{
    accept a client connection
    fork
    if (child)
    {
        communicate with new socket
        close new socket
        exit
     }
 else
 {close new socket}
}

From what I've seen, the "communicate with new socket" part consists of reading the buffer and then possibly writing to the buffer, then the socket closes. I thought sockets were suppose to be a persistent connection? If the client has to reconnect every time it wants to send more data to the server, isn't this inefficient and defeating the purpose of sockets?

You should be using an event library such as libevent or libev. — Per Johansson
You don't need to fork for every client. You very probably need an event loop around a multiplexing syscall like select or poll (or a library with an event loop, like libev or libevent or something else; and that library would do the multiplexing). — Basile Starynkevitch

NPE NPE · Accepted Answer · 2012-02-07T10:38:42

If the client has to reconnect every time it wants to send more data to the server, isn't this inefficient and defeating the purpose of sockets?

It's impossible to say without knowing more about the nature of your application:

In some cases, it makes sense to maintain a persistent connection for the duration of the client's lifetime.
In other cases, connecting on every message would also work well.

You are quite right on the efficiency front: there is quite a lot of overhead involved in establishing a TCP connection. Therefore, if the messages are frequent it may turn out to be very costly to set up a new connection for each message.

C/Linux TCP Socket Server

2 Answers