Qt5 cross-threads signal and slot

Question

Before this question is closed as duplicate: The question that was asked about this same problem is from 2009 and Qt changed how threading should be implemented.

My Qt application has a main thread and a worker thread. I simplified the code for the question, but the problem is as follows:

If The MainWindow object emits a signal, that must be received by the slot of the worker object in a different QThread.

The main functions looks as follows:

int main(int argc, char *argv[])
{
    QApplication a(argc, argv); 
    MainWindow w(0, [lot of irrelevant argumtents], ...)

    QThread* thread = new QThread;
    Worker *worker = new Worker(&w);
    QObject::connect(&w, SIGNAL(demoButtonClicked()), worker, SLOT(DemoButton()));
    QObject::connect(thread, SIGNAL(started()), worker, SLOT(process()));
    worker->moveToThread(thread);
    thread->start();

    w.show();
    a.exec();
}

The (simplified) worker class looks as follows:

class Worker : public QObject
{
    Q_OBJECT
public:
    Worker(MainWindow *w);
public slots:
    void process();
    void DemoButton();
};


void Worker::DemoButton(){
    cout << "Slot for demo button executed from worker thread!" << endl;
}

And the mainwindow class contains this function and just the signal defined in the header:

void MainWindow::on_pushButton_3_clicked()
{
    std::cout << "Signal for demo button emitted!" << std::endl;
    emit demoButtonClicked();
}

When I exectute the program, the on_pushButton_3_clicked function is executed, but not the slot in the worker object.

Answer 1

发现问题， Worker::process确实阻塞了事件循环。