一个工人可能在Qt中通过信号/插槽连接来停止自己的线程吗？

Question

I'm trying to implement threaded worker for parallel computation. The problem I encountered is that the quit() slot of thread is not triggered, therefore applications waits at while(thread->isRunning()) . Is it possible to stop thread from worker using signal-slot connection between them? Here is my code:

main.cpp:

#include <QCoreApplication>
#include "workermanager.h"

int main(int argc, char *argv[])
{
    QCoreApplication a(argc, argv);
    WorkerManager workerManager;
    workerManager.process();
    return a.exec();
}

worker.h:

#include <QObject>
#include <QDebug>

class Worker : public QObject
{
   Q_OBJECT
public:
    explicit Worker(QObject *parent = 0) :
        QObject(parent){}

signals:
    void processingFinished();

public slots:
    void process()
    {
        qDebug() << "processing";
        emit this->processingFinished();
    }
};

workermanager.h:

#include "worker.h"
#include <QThread>

class WorkerManager : public QObject
{
    Q_OBJECT
public:
    explicit WorkerManager(QObject *parent = 0) :
        QObject(parent){}

    void process()
    {
        QThread* thread = new QThread;
        Worker* worker = new Worker;

        connect(thread,SIGNAL(started()),worker,SLOT(process()));
        connect(worker,SIGNAL(processingFinished()),thread,SLOT(quit()));

        worker->moveToThread(thread);
        thread->start();
        qDebug() << "thread started";
        while(thread->isRunning())
        {
        }
        qDebug() << "thread finished";

       //further operations - e.g. data collection from workers etc.

    }
};

Answer 1

That while loop blocks your thread and prevents it from processing any signals, if you really want to wait for the thread to finish, you need to start an event loop.

Try this instead:

void process()
{
    QThread* thread = new QThread;
    Worker* worker = new Worker;

    connect(thread,SIGNAL(started()),worker,SLOT(process()));
    connect(worker,SIGNAL(processingFinished()),thread,SLOT(quit()));

    worker->moveToThread(thread);

    QEventLoop loop;
    connect(thread, &QThread::finished, &loop, &QEventLoop::quit);
    qDebug() << "thread started";
    thread->start();
    loop.exec();
    qDebug() << "thread finished";

   //further operations - e.g. data collection from workers etc.

}

But I have to admit I don't really see the point of this code. If you need to wait for the task to finish to keep doing stuff, you might as well run it directly. There at least your program will be able to process other things (if there are some) in the mean time.