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Issue description

I’m writing a simple test program using router dealer pattern as follow.(using c or cppzmq has the same problem)

int main()
{
    zmq::context_t context(1);
    zmq::socket_t router(context, ZMQ_ROUTER);
    router.bind("tcp://*:5555");

    zmq::pollitem_t items [] = {
            { router, 0, ZMQ_POLLIN, 0 }
    };

    int recvCount = 0;
    const int maxCount = 10e4;

    s_console("start");
    while(true)
    {
        zmq::poll(items, 1, -1);
        if (items[0].revents & ZMQ_POLLIN)
        {
            //nothing todo, just receving
            std::string identify = s_recv(router);
            std::string msg = s_recv(router);

            ++recvCount;

            if (recvCount == maxCount)
            {
                s_console("recv %d messages!", maxCount);
                break;
            }
        }
    }
}

If I comment the code //zmq::poll(items, 1, -1); // if (items[0].revents & ZMQ_POLLIN) receive 100000 simple string msg using just 200~300ms, but if I add the poll code, receive 100000 msg using 40+ seconds.

where is the problem? Thanks

Environment

• libzmq version (commit hash if unreleased): 4.0.2
• OS: Windows

Minimal test code / Steps to reproduce the issue

as the issue’s description

What’s the actual result? (include assertion message & call stack if applicable)

If I comment the code //zmq::poll(items, 1, -1); // if (items[0].revents & ZMQ_POLLIN) receive 100000 simple string message using just 200~300ms, but if I add the poll code, receive 100000 messages using 40+ seconds.

What’s the expected result?

add zmq::poll(items, 1, -1); if (items[0].revents & ZMQ_POLLIN), and receive 100000 messages using 300 ms, not 40+ seconds.