Question

I wrote a small server program. I wanted to see how it is handling multiple requests. So I wrote the following program to simulate multiple clients.

Pseudo Code:

main()
{

    //set up all necessary data structures to connect to the server

    fork();
    fork();
    fork();

    create_socket();
    connect()

    //more code

}

Is there a better way of doing it? What tools I can use to test multi threaded program in C(at least the basic functionality)?

Answer 1

You’ve basically created a “process-fan” with this approach, so yes, that can work, although it’s not threading … you’re actually creating new processes. Therefore you will want, in order to prevent zombie child processes, to “wait” for all processes to complete in each process that has spawned a new process. You could do this with the following line at or near the end of your main() for all processes that have called fork() (i.e., include the child-processes as well since they are spawning additional processes):

while(wait(NULL) != -1 || errno == EINTR);

This will wait for all the child-processes the current process has spawned, while preventing any early returns of wait() due to your process catching a signal. When there are no remaining child-processes for the current process, then wait() will return -1 and set errno to ECHILD, thus exiting the while-loop.