Why am I getting many “RemoteHostClosedError” sending a POST over HTTP?



  • Hello,

    I am trying to interact with a virtual reality software, NeuroVR. This software has a HTTP server and the user can send data through it. The server can be accessed by the localhost:8888. If access over a browser, there is a form to submit data. The type of data is a connector name and a connector value. So, I created a Qt5.5 console program to send data for the NeuroVR.

    My problem: I am sending data each 4 seconds (more or less) and I am getting many "RemoteHostClosedError" as reply. In some cases I had sucess with an "HttpStatusCodeAttribute" equal 200, but the rate of success sometimes is less than 50%.

    I thought that the problem was the server. So I made tests over the browser accessing the localhost:8888 sending data each 1(max of 2) secs. The server accepted all, it was perfect.
    My program is based on this tutorial: Sending a HTTP request using Qt 5 framework

    My QNetworkAccessManager and QNetworkRequest are attributes of the class. They are allocated at the constructor.

    this->request = new QNetworkRequest(QUrl(this->nvrhost));
    request->setHeader(QNetworkRequest::ContentTypeHeader,"application/x-www-form-urlencoded");
    this->manager = new QNetworkAccessManager(this);
    connect(this->manager,SIGNAL(finished(QNetworkReply*)),this,SLOT(replyNVR(QNetworkReply*)));
    this->evLoop = new QEventLoop(this);
    connect(this->manager,SIGNAL(finished(QNetworkReply*)),this->evLoop,SLOT(quit()));

    This method sends the request to the server:

    void BciSocket::sendToNvr(QString data, QString connector)
    {
    QUrlQuery query;
    query.addQueryItem("connectorID",connector);
    query.addQueryItem("connectorValue",data);
    this->manager->post((*request),query.toString(QUrl::FullyEncoded).toUtf8());
    this->evLoop->exec();
    }

    My question: Why this is happening and how to can I avoid it? How to can I improve it?

    Thanks for your attention!


  • Lifetime Qt Champion

    Hi,

    Why are you creating your request on the heap rather than stack ?

    Also, you never delete the request so you might be covering one with another and you have a memory leak.



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