inter thread comunication using ZeroMQ messages [closed]

问题

I am trying to use zeroMQ as a way to implement a messaging system between multiple threads. I tried the code below but it doesn't work; in the specific the call to zmq_recv in each thread doesn't wait/block for any message to be executed.

Can you help me with this piece of code?

I am using Linux OS and gcc

Best Regards

AFG

    static void *
    worker_routine (void *context) {
        // Socket to talk to dispatcher
        void *receiver = zmq_socket (context, ZMQ_REP);
        zmq_connect (receiver, "inproc://workers");
        while (1) {

            zmq_msg_t request;
            zmq_msg_init( &request );
            zmq_recv( receiver, &request, 0 );
            printf ("Received request\n");
            // Do some 'work'
            usleep (1000);
            // Send reply back to client
            zmq_send (receiver, &request, 0);
        }
        zmq_close (receiver);
        return NULL;
    }

    int main (void) {

    void *context = zmq_init (1);
    void *clients = zmq_socket (context, ZMQ_REP);
    zmq_bind (clients, "inproc://workers");

    int thread_nbr;
    for (thread_nbr = 0; thread_nbr < 5; thread_nbr++) {
        pthread_t worker;
        pthread_create (&worker, NULL, worker_routine, context);
    }

    zmq_close (clients);
    zmq_term (context);
    return 0;
    }

回答1:

Both sockets are REP. What you want is REQ + REP.

回答2:

You're shutting down the socket and ZeroMQ right after you're creating the threads. They probably don't have time to reach a blocking state, and if they did, they would fail as soon as you destroy the zmq context. From the zmq_term man page:

Context termination is performed in the following steps:

Any blocking operations currently in progress on sockets open within context shall return immediately with an error code of ETERM.

回答3:

Firstly, as @sustrik noted you need to use REQ and REP, both the main thread and the worker threads cannot be REP.

Secondly, you need to provide some sort of blocking loop in your main thread:

int main (int argc, char **argv)
{
    void *context = zmq_init (1);
    void *clients = zmq_socket (context, ZMQ_REP); // use ZMQ_REQ on the clients
    zmq_bind (clients, "inproc://workers");

    int thread_nbr;
    for (thread_nbr = 0; thread_nbr < 5; thread_nbr++) {
        pthread_t worker;
        pthread_create (&worker, NULL, worker_routine, context);
    }

    while (TRUE)
    {
        // worker thread connected asking for work
        zmq_msg_t request;
        zmq_msg_init (&request);
        zmq_recv (clients, &request, 0);
        zmq_msg_close (&request);

        // do whatever you need to do with the clients' request here

        // send work to clients
        zmq_msg_t reply;
        zmq_msg_init_data (&reply, "Reply", 5, NULL, NULL);
        zmq_send (clients, &reply, 0);
        zmq_msg_close (&reply);
    }

    zmq_close (clients);
    zmq_term (context);
    return 0;
}

来源：https://stackoverflow.com/questions/5476308/inter-thread-comunication-using-zeromq-messages

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zeromq