Execution freezes when sending QRunnable to QThreadpool

John Howe

In my application, I receive data from a signal in a slot call at a rate of 60Hz. To improve performance, I'm trying to break off chunks of data and send it to be processed in various QRunnables via QThreadpool.

Right now I am just trying to implement the Hello World task from the QThreadPool page.

As I've got it laid out, I should be getting Hello World every time the slot is called. But instead it runs one time and then the application freezes. Any ideas?

J.Hilk

@John-Howe said in Execution freezes when sending QRunnable to QThreadpool:

Any ideas?

You're ding something wrong ? 😜

We will probably need code snippets to tell you anything remotely of value

John Howe

From my .h:

class HelloWorldTask : public QRunnable
{
    void run() override;
};

Implementation:

void HelloWorldTask::run()
{
    qDebug() << "Hello world from thread" << QThread::currentThread();
}

Slot call (signal comes at 60Hz):

            HelloWorldTask *hello = new HelloWorldTask();
            pool->tryStart(hello);

J.Hilk

@John-Howe
works fine by me

class HelloWorldTask : public QRunnable
{

public:
    void run() override
    {
        while (true) {
            QThread::msleep(16);//60Hz, ca.
            qDebug() << "Hello world from thread" << QTime::currentTime() << QThread::currentThread();
        }

    }
};

int main(int argc, char *argv[])
{
    QApplication app(argc, argv);
//    QCoreApplication app(argc, argv);

    QLabel responsiveLabel("Move me");
    responsiveLabel.resize(200,200);
    responsiveLabel.show();

    HelloWorldTask *hello = new HelloWorldTask();
    // QThreadPool takes ownership and deletes 'hello' automatically
    QThreadPool::globalInstance()->tryStart(hello);

    return  app.exec();
}