[zeromq-dev] Crosstalk between sockets

david.myers at avalesta.com david.myers at avalesta.com
Fri Sep 1 16:12:03 CEST 2017


>>Can you upload a code snippet that reproduces the issue to
>>pastebin/gist/etc?

>>-- 
>>Kind regards,
>>Luca Boccassi

Thanks Luca, 

So the client threads look basically like this:- 

    zmq::context_t context(1);
    char szBuf[32];
    // Start Image socket
    m_socketImg = new zmq::socket_t(context, ZMQ_REP);
    sprintf_s(szBuf, "tcp://*:%d", m_PortNumberImg); 

    m_socketImg->bind(szBuf);
    // Set timeout for Image socket
    m_socketImg->setsockopt(ZMQ_RCVTIMEO, 1000); 

    imageDataHeader ImageHeader;
    zmq::message_t ImgHdr((void*)&ImageHeader, sizeof(ImageHeader),
(zmq::free_fn*)EmptyFreeFunct); 

     zmq::message_t ImgData;
     try
    {
         m_socketImg->recv(&ImgData);
     }
     catch (...)
     {
         TRACE(_T("ZMQ Img error\n"));
     } 

     try
     {
            m_socketImg->send(ImgAck);
      }
      catch (...)
      {
            TRACE(_T("ZMQ Img Ack error\n"));
      } 

The server processes look like this:- 

    char sImageUrl[32];
    sprintf_s(sImageUrl, "tcp://localhost:%d", m_PortNumberImg); 

    m_psocketImage = new zmq::socket_t (context, ZMQ_REQ);
    m_psocketImage->setsockopt(ZMQ_SNDHWM, 100);
    m_psocketImage->connect(sImageUrl);
    m_psocketImage->setsockopt(ZMQ_RCVTIMEO, 1000); 

    //now send image data
    zmq::message_t imagemessage(imageData->pvData, imageDataLen,
empty_free, (void *)&h1);
     try
    {
        m_ZmqThread->m_psocketImage->send(imagemessage);
    }
    catch (const zmq::error_t& ze)
    {
        TRACE(("ZMQ error sending image data: %s\n"), ze.what());
    } 

    //wait for response (not required as we are now a ZMQ_PUSH)
    zmq::message_t response;
    try
    {
        bool bRet = m_ZmqThread->m_psocketImage->recv(&response);
    }
    catch (const zmq::error_t& ze)
    {
        TRACE(_T("ZMQ error receiving image response: %ws\n"),
ze.what());
    } 

The above REQ-REP code works well but when I rewrite it using PUSH-PULL
or PUB-SUB or PAIR (removing the Acknowledge code), the server processes
crash when the second one connects, after a number of frames. 

- David
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