How to make two WebSocket servers listen on the same port?

[江源]

I create two threads and each runs a WebSocket server. Both listen on the same port.

When i run the below example, an error message shows "Address already in use".  

Thanks a lot~!

int main()

{

    int thread_num = 2;

    pthread_t tids[thread_num];

    

    for (int i = 0; i < thread_num; i++) {

        if (pthread(&tids[i], NULL, CreateServer, NULL) != 0) {

            cout << "Create WebSocket server " << i << ":failed!" << endl;

        }

    }

    

    pthread_exit(NULL);

    return 0;

}

void* CreateServer()

{

    // Create a server endpoint

    server echo_server;

    // Initialize ASIO

    echo_server.init_asio();

    // Register our message handler

    echo_server.set_message_handler(bind(&on_message,&echo_server,::_1,::_2));

    echo_server.set_http_handler(bind(&on_http,&echo_server,::_1));

    echo_server.set_tls_init_handler(bind(&on_tls_init,MOZILLA_INTERMEDIATE,::_1));

    echo_server.set_reuse_addr(true);

    // Listen on port 9002

    echo_server.listen(9002);

    // Start the server accept loop

    echo_server.start_accept();

    // Start the ASIO io_service run loop

    echo_server.run();

}

[Peter Thorson]

Generally, you cannot have two servers listen on the same port of the same IP address as there is no way to determine which server should receive each connection. What are you trying to do?

If you just want a single server with a single listening socket on a single port to have its handlers served by multiple threads you can do that.

If you want to run multiple fully identical servers on a single port you can generate two servers on different ports and use load balancing software like HAProxy to split up traffic between them.