Question

I’ve made a piece of code in what’s on my server as multiple threads

The problem is that it doesn’t send data while im receiving on the other socket.

so if i send something from to client 1 to client 2, client2 only receives if he sends something himself(jumps out of the recv function) .. how can i solve this ?

 /* Thread*/
while (! stop_received) {
        nr_bytes_recv = recv(s, buffer, BUFFSIZE, 0);

        if(strncmp(buffer, "SEND", 4) == 0) {
            char *message = "Text asads \n";
            rv = send(users[0].s, message, strlen(message), 0);
            rv = send(users[1].s, message, strlen(message), 0);
            if (rv < 0) {
                perror("Error sending");
                exit(EXIT_FAILURE);
            }           
        }else{
            char *message = "Unknown command \n";
            rv = send(s, message, strlen(message), 0);
            if (rv < 0) {
                perror("Error sending");
                exit(EXIT_FAILURE);
            }
        }
}

Answer 1

To be a little more specific, there are a few types of I/O. What you’re doing currently is called blocking i/o. In general that means that when you call send or recv the operation will “block” until it has completed.

In contrast to that there is what is known as non-blocking i/o. In this i/o model an operation will return immediately if it’s unable to complete. Typically the select function is used with this i/o model.

You can see an example program here at the Select Tutorial. The full source code is at the bottom of the page.

As others have noted, your other option is to use threads.