Qt6 Windows slower than Qt6 Ubuntu

[Joe von Habsburg]

@JonB
I watch debug line and graphic. The data which is came, it's graphic data and I draw i it (drawing is 30ms).

Debug line :

qDebug() << "sample : " << time3 - time1 << " iq : " << time2 - time3 << "time : " << time2 - time1;

In ubuntu : 150ms 0ms 150ms
In windows : 400ms 0ms 400ms

How can I take data with different way ? Can you give any example?

Note: The data is come with only get request.

[JonB]

@Joe-von-Habsburg
I have suggested what you should test first, but you have said nothing each time.. I also suggested you do not test anything with the "debug" in "debug line and graphic".

[Joe von Habsburg]

@JonB I run release versions, and I saw same thing. Any advice for get request ? And is it possible, gcc more performance than msvc ?

[JonB]

@Joe-von-Habsburg
No, compiler is not going to make any difference when fetching data over a network and it's taking hundreds of milliseconds.

[Joe von Habsburg]

@JonB

I wrote basic program just taking data. (Because I suspect other code lines slow me). I saw same output.

Can you give me code example for get request ?

[JonB]

@JonB said in Qt6 Windows slower than Qt6 Ubuntu:

How do timings compare on each platform quite outside of a Qt program?

[Joe von Habsburg]

@JonB I watched graphic speed

[jsulm]

@Joe-von-Habsburg You should read more carefully what others write. What @JonB suggested is that you try to get the data with a non Qt application on both platforms to see whether the behaviour is the same or not...

[Joe von Habsburg]

@jsulm I used javascript for get request.

const deneme = async() => {
    while(true){
        var date1 = new Date();
    
        var res = await fetch('http://localhost:54664/sample')
        var data = await res.json();
        console.log("sample len : ",data.samples[0].length)
    
        var date2 = new Date();
    
        var res2 = await fetch('http://localhost:54665/sample')
        var data2 = await res2.json();
        console.log("sample len : ",data2.samples[0].length)
    
        var date3 = new Date();
    
        console.log("sample : ", date2-date1, " - iq : ", date3 - date2, " - time : ", date3 - date1);
    }
}


deneme();

I saw same times between ubuntu and windows (90ms).
I think the problem is in windows Qt. Any idea ?

[jsulm]

@Joe-von-Habsburg You should try to do your networking properly: without local event loops. Qt is asynchronous.

[Christian Ehrlicher]

... And you should/must not recreate the QNetworkAcceesManager every time.

[Joe von Habsburg]

@Christian-Ehrlicher said in Qt6 Windows slower than Qt6 Ubuntu:

And you should/must not recreate the QNetworkAcceesManager every time.

This work for me. Thank you so much :)

[Joe von Habsburg]

@Christian-Ehrlicher

I have another question. I received some times between ubuntu and windows (65ms). Everything is ok. But, sometimes windows rising 350ms for one packet. In ubuntu just max 80ms.

QByteArray DataReceiver::getData(int port)
{
    QString url = QString("http://localhost:%1/sample").arg(port);
    _apiUrl.setUrl(url);
    _request.setUrl(_apiUrl);
    _reply = _manager.get(_request);
    connect(_reply, &QNetworkReply::finished, &_loop, &QEventLoop::quit);
    _loop.exec();
    if (_reply->error() == QNetworkReply::NoError) {
        QByteArray responseData = _reply->readAll();
        _reply->deleteLater();
        return responseData;
    } else {
        QString _error = tr("Error");
        QString _spectrum_error = tr("Spectrum error.");
        QMessageBox::critical(nullptr, _error, _spectrum_error);
        stop();
    }
    _reply->deleteLater();
    return NULL;
}

Do you know, why it's rising ? What can I do another, after take data ?

[Joe von Habsburg]

@Joe-von-Habsburg I found the reason. Thanks a lot :) <3

[Volker75]

@Joe-von-Habsburg And what was the reason? Windows defender?

[Joe von Habsburg]

@Volker75 said in Qt6 Windows slower than Qt6 Ubuntu:

And what was the reason? Windows defender?

another networkmanager.....

@Christian-Ehrlicher , @JonB , @jsulm

Hi guys, I need your help. When I run the my program (only data receive) after 30min, my ram will be 20gb. It's increase always. I tested it in Ubuntu and Windows and I saw same thing. What should I do after take data?

QByteArray DataReceiver::getData(int port)
{
    QString url = QString("http://localhost:%1/sample").arg(port);
    _apiUrl.setUrl(url);
    _request.setUrl(_apiUrl);
    reply = _manager.get(_request);
    connect(reply, &QNetworkReply::finished, &_loop, &QEventLoop::quit);
    _loop.exec();
    if (reply->error() == QNetworkReply::NoError) {
        QByteArray responseData = reply->readAll();
        reply->deleteLater();
        return  responseData;
    } else {
        QString _error = tr("Error");
        QString _spectrum_error = tr("Spectrum error.");
        QMessageBox::critical(nullptr, _error, _spectrum_error);
        stop();
    }
    reply->deleteLater();
    return {};
}

if I use my code like that :

QByteArray DataReceiver::getData(int port)
{
    QString url = QString("http://localhost:%1/sample").arg(port);
    QUrl _apiUrl(url);
    QNetworkRequest _request(_apiUrl);
    QEventLoop _loop;
    QNetworkAccessManager _manager;
    QNetworkReply *reply = _manager.get(_request);
    connect(reply, &QNetworkReply::finished, &_loop, &QEventLoop::quit);
    _loop.exec();
    if (reply->error() == QNetworkReply::NoError) {
        QByteArray responseData = reply->readAll();
        reply->deleteLater();
        return  responseData;
    } else {
        QString _error = tr("Error");
        QString _spectrum_error = tr("Spectrum error.");
        QMessageBox::critical(nullptr, _error, _spectrum_error);
        stop();
    }
    reply->deleteLater();
    return {};
}

Memory will not rise but response time slow....

[JonB]

@Joe-von-Habsburg
Is the difference due to the QNetworkAccessManager _manager; or to the QNetworkReply *reply = _manager.get(_request);?
In the bad case you might connect to reply->destroyed() to make sure it is indeed getting freed.

[Joe von Habsburg]

@JonB

According to my tests, if I rebuild the NetworkManager, my memory usage does not increase. But this time my receiving time is slowing down.

If I do not recreate the NetworkManager, my reception time decreases but memory usage increases.

connect(reply, &QNetworkReply::destroyed, this, &DataReceiver::replyDeleted);

it's work, reply deleted

[JonB]

@Joe-von-Habsburg
In that case please replace the second one's QNetworkReply *reply = _manager.get(_request); with the first one's reply = _manager.get(_request); (I assume reply is a member variable, this->reply) and confirm. Then the only difference is the local QNetworkAccessManager _manager versus a class member one.

[Joe von Habsburg]

@Joe-von-Habsburg said in Qt6 Windows slower than Qt6 Ubuntu:

connect(reply, &QNetworkReply::destroyed, this, &DataReceiver::replyDeleted);

sorry for that. this is work only when I stop my while loop. How can force it ?

@Joe-von-Habsburg said in Qt6 Windows slower than Qt6 Ubuntu:

 void DataReceiver::start()
 {
     _connection++;
     if(_connection > 1)
         return;
 
     qDebug() << "Starting take data";
     _takeData = true;
     while(_takeData){
         QDateTime time1 = QDateTime::currentDateTime();
         _sample = getData(54664);
         QDateTime time3 = QDateTime::currentDateTime();
         if(_takeIQData)
             _iq = getData(54665);
         QDateTime time2 = QDateTime::currentDateTime();
         qDebug() << "sample : " << time3 - time1 << " iq : " << time2 - time3 << "time :  << time2 - time1;
        emit sendData(_sample, _iq);
     }
     qDebug() << "Finished taking data";
 }

@JonB said in Qt6 Windows slower than Qt6 Ubuntu:

n that case please replace the second one's QNetworkReply *reply = _manager.get(_request); with the first one's reply = _manager.get(_request); (I assume reply is a member variable, this->reply) and confirm. Then the only difference is the local QNetworkAccessManager _manager versus a class member one.

I change it.
_reply and _manager class member now

QByteArray DataReceiver::getData(int port)
{
    QString url = QString("http://localhost:%1/sample").arg(port);
    QUrl _apiUrl(url);
    QNetworkRequest _request(_apiUrl);
    QEventLoop _loop;
    _reply = _manager.get(_request);
    connect(_reply, &QNetworkReply::finished, &_loop, &QEventLoop::quit);
    connect(_reply, &QNetworkReply::destroyed, this, &DataReceiver::replyDeleted);
    _loop.exec();
    if (_reply->error() == QNetworkReply::NoError) {
        QByteArray responseData = _reply->readAll();
        _reply->deleteLater();
        return  responseData;
    } else {
        QString _error = tr("Error");
        QString _spectrum_error = tr("Spectrum error.");
        QMessageBox::critical(nullptr, _error, _spectrum_error);
        stop();
    }
    _reply->deleteLater();
    return {};
}

The problem still exists.

I think lots of reply are created and they only delete I stop my loop.