Why i can't send more then 1 http request in parallel in the same main thread



  • Hi ,
    i just noticed that when i try to send http request while there are already http request
    going on in the background . one of them stooping and whiting until the previous will end.
    they both use there own QNetworkAccessManager.



  • From the docs:
    Note: QNetworkAccessManager queues the requests it receives. The number of requests executed in parallel is dependent on the protocol. Currently, for the HTTP protocol on desktop platforms, 6 requests are executed in parallel for one host/port combination.

    And I think it would be better to use a single QNetworkAccessManager.



  • i must doing here something wrong and i don't know , here some code .
    there are 2 http post functions the first is simple post that invoked every 5 sec
    and the second one is file upload post function that call in parallel.
    when i call the file upload the first stops , whits until the file upload finished and continue this is come's from Qt with out my intervention .
    this is with single QNetworkAccessManager

    @ //Init in the class contractor

    networkManager = new QNetworkAccessManager(this);
    connect(networkManager,SIGNAL(sslErrors(QNetworkReply*,QList<QSslError>)), this, SLOT(on_sslErr(QNetworkReply*,QList<QSslError>)));

    //-----------------------------------------------------\

    //this is upload file code , its taking time untill it finish working great

    PostImageRequest( QString& Response,
    QMap<QString,QString> paramsToPostMap,
    QString& BaseUrl,
    QString imageFullPath,
    int iTimeOutInterval)

    QByteArray imageFormat = QImageReader::imageFormat(imageFullPath);
    QString imageMimeType(imageFormat);
    QNetworkRequest request;
    QUrl params;
    QMapIterator<QString,QString> i(paramsToPostMap);
    while (i.hasNext()) {
    i.next();
    addField(i.key(),i.value());
    }

    addFile("file",imageFullPath,imageMimeType);
    QString crlf="\r\n";
    qsrand(QDateTime::currentDateTime().toTime_t());
    QString b=QVariant(qrand()).toString()+QVariant(qrand()).toString()+QVariant(qrand()).toString();
    QString boundary="---------------------------"+b;
    QString endBoundary=crlf+"--"+boundary+"--"+crlf;
    QString contentType="multipart/form-data; boundary="+boundary;
    boundary="--"+boundary+crlf;
    QByteArray bond=boundary.toAscii();
    QByteArray send;
    bool first=true;

    for (int i=0; i<fieldNames.size(); i++) {
    send.append(bond);
    if (first) {
    boundary=crlf+boundary;
    bond=boundary.toAscii();
    first=false;
    }
    send.append(QString("Content-Disposition: form-data; name=""+fieldNames.at(i)+"""+crlf).toAscii());
    if (encodingS=="utf-8") send.append(QString("Content-Transfer-Encoding: 8bit"+crlf).toAscii());
    send.append(crlf.toAscii());
    send.append(strToEnc(fieldValues.at(i)));
    }
    for (int i=0; i<files.size(); i++) {
    send.append(bond);
    send.append(QString("Content-Disposition: form-data; name=""+fileFieldNames.at(i)+""; filename=""+fileNames.at(i)+"""+crlf).toAscii());
    send.append(QString("Content-Type: "+fileMimes.at(i)+crlf+crlf).toAscii());
    send.append(files.at(i));
    }

    send.append(endBoundary.toAscii());

    fieldNames.clear();
    fieldValues.clear();
    fileFieldNames.clear();
    fileNames.clear();
    fileMimes.clear();
    files.clear();
    request.setHeader(QNetworkRequest::ContentTypeHeader, contentType.toAscii());
    request.setHeader(QNetworkRequest::ContentLengthHeader, QVariant(send.size()).toString());
    request.setUrl(BaseUrl);

    if(iTimeOutInterval != -1)
    {
    QEventLoop loop2;
    QTimer::singleShot(iTimeOutInterval, &loop2, SLOT(quit()) );
    loop2.exec();
    }
    QEventLoop loop;
    QNetworkReply *reply = networkManager->post(request,send);
    connect(reply, SIGNAL(uploadProgress(qint64,qint64)), this,SLOT(SetProgress(qint64,qint64)));
    connect(reply, SIGNAL(finished()), &loop, SLOT(quit()));
    loop.exec();
    //return response
    QNetworkReply::NetworkError networkError = reply->error();
    HandleNetworkError(networkError);
    Response.clear();
    QByteArray data=reply->readAll();
    Response.append(data);
    //delete reply;
    reply->deleteLater();

    //--------------------------------------------------------------------------------\

    //this is the post function that invoket every 5 secound
    

    PostRequest(QString& Response,
    QMap<QString,QString> paramsToPostMap,
    QString& BaseUrl,
    int iTimeOutInterval)

    QNetworkRequest request;
    QUrl params;
    QMapIterator<QString,QString> i(paramsToPostMap);
    while (i.hasNext()) {
    i.next();
    params.addQueryItem(i.key(),i.value());
    }
    request.setUrl(BaseUrl);

    QByteArray postArgs;
    postArgs = params.encodedQuery();

    if(iTimeOutInterval != -1)
    {
    QEventLoop loop2;
    QTimer::singleShot(iTimeOutInterval, &loop2, SLOT(quit()) );
    loop2.exec();
    }
    QEventLoop loop;
    QNetworkReply *reply = networkManager->post(request,postArgs);
    connect(reply, SIGNAL(finished()), &loop, SLOT(quit()));
    loop.exec();
    //return response
    QNetworkReply::NetworkError networkError = reply->error();
    HandleNetworkError(networkError);
    Response.clear();
    QByteArray data=reply->readAll();
    Response.append(data);

    //delete reply;
    reply->deleteLater();@



  • I'm 99% sure that it's because you're using two QEventLoops (I don't know exactly why it's hapenning and it might have something to do with the code you use to call the second function ever 5 seconds). Therefore, yous should probably use two separate slots for handling the replies instead of the event loops.



  • but its is 2 functions , the scope of the QEventloop is local to its function


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