QThread Proper Use ?? connect Problems....

[GuiHanoi]

Hi everyone,

I'm new on this forum. I'm using Qt4.8.6 for its GUI performances but now I want to use QThreads properly. I saw on the web different ways to declare and use them.

- redefinition of methods run() of Object inheriting of QThread class => Wrong way

- definition of a Worker and worker->moveToThread (QThread*) => Right way ??? (https://forum.qt.io/topic/14378/my-t...y-use-qthreads)

I developed a small project with these two methods to compare them. threadA which displays "A" and threadB which displays "B". To start/stop each threads, there are buttons. Both of these methods work (displaying AAAAA when AButton pushed, BBBBBBB when BButton pushed and ABABABABABA when both are pushed...

BUT if I follow steps of the second method (Correct use), I must connect :

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

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

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but when I add these two connections, I have : Violation of Ox0FFFFFFFF emplacement Mutex....

connect(worker, SIGNAL(finished()), worker, SLOT(deleteLater())); 
connect(thread, SIGNAL(finished()), thread, SLOT(deleteLater()));

connect(worker, SIGNAL(finished()), worker, SLOT(deleteLater())); 
connect(thread, SIGNAL(finished()), thread, SLOT(deleteLater()));

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How can I do to make this error disappear ?
Other question, in my code when i'm displaying threadID, it always displays 00000000159 (for example), for both threads ! I think I'm missing something.... Thread must NOT have the same ID ???? principles ??? (same problem in the two methods)

this is my code, without hpp files :
-------------------------------------------
Worker.cpp

Worker::Worker() { stopped = false;} // attribute of Worker instance
 
void Worker::process()
{
   while (!stopped)
      std::cout << messageStr.toStdString(); // attribute of Worker instance
  emit finished();
}
 
void Worker::stop() { stopped = true;}
void Worker::start() {stopped = false;}

Worker::Worker() { stopped = false;} // attribute of Worker instance

void Worker::process()
{
   while (!stopped)
      std::cout << messageStr.toStdString(); // attribute of Worker instance
  emit finished();
}

void Worker::stop() { stopped = true;}
void Worker::start() {stopped = false;}

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---------------------------------------------
ThreadDialog.cpp

ThreadDialog::ThreadDialog(QWidget *parent) : QDialog(parent)
{
	workerA = new Worker();
	workerB = new Worker();
 
	threadAButton = new QPushButton(tr("Start A"));
	threadBButton = new QPushButton(tr("Start B"));
	quitButton = new QPushButton(tr("Quit"));
	quitButton->setDefault(true);
 
	threadA = new QThread;
	workerA->setMessage("A ");
	workerA->moveToThread(threadA);
 
	threadB = new QThread;
	workerB->setMessage("B ");
	workerB->moveToThread(threadB);
 
	connect(threadA, SIGNAL(started()), workerA, SLOT(process()));
	connect(workerA, SIGNAL(finished()), threadA, SLOT(quit()));
	//connect(workerA, SIGNAL(finished()), workerA, SLOT(deleteLater()));
	//connect(threadA, SIGNAL(finished()), threadA, SLOT(deleteLater()));
 
	connect(threadB, SIGNAL(started()), workerB, SLOT(process()));
	connect(workerB, SIGNAL(finished()), threadB, SLOT(quit()));
	//connect(workerB, SIGNAL(finished()), workerB, SLOT(deleteLater()));
	//connect(threadB, SIGNAL(finished()), threadB, SLOT(deleteLater()));
 
   connect(threadAButton, SIGNAL(clicked()), this, SLOT(startOrStopThreadA()));
   connect(threadBButton, SIGNAL(clicked()), this, SLOT(startOrStopThreadB()));
   connect(quitButton, SIGNAL(clicked()), this, SLOT(close()));
   .... // displayLayout
}
 
void ThreadDialog::startOrStopThreadA()
{
   if (threadA->isRunning()) 
   {
       workerA->stop();
       threadAButton->setText(tr("Start A"));
   } 
   else 
   {
	   std::cout << threadA->currentThreadId() << std::endl;
	   workerA->start();
       threadA->start();
       threadAButton->setText(tr("Stop A"));
   }
}
 
void ThreadDialog::startOrStopThreadB()
{
   if (threadB->isRunning()) 
   {
       workerB->stop();
       threadBButton->setText(tr("Start B"));
   } 
   else 
   {
	   std::cout << threadB->currentThreadId() << std::endl;
	   workerB->start();
       threadB->start();
       threadBButton->setText(tr("Stop B"));
   }
}
 
void ThreadDialog::closeEvent(QCloseEvent *event)
{
   workerA->stop();
   workerB->stop();
   threadA->wait();
   threadB->wait();
   threadA->exit();
   threadB->exit();
 
   event->accept();
}

ThreadDialog::ThreadDialog(QWidget *parent) : QDialog(parent)
{
	workerA = new Worker();
	workerB = new Worker();

	threadAButton = new QPushButton(tr("Start A"));
	threadBButton = new QPushButton(tr("Start B"));
	quitButton = new QPushButton(tr("Quit"));
	quitButton->setDefault(true);

	threadA = new QThread;
	workerA->setMessage("A ");
	workerA->moveToThread(threadA);

	threadB = new QThread;
	workerB->setMessage("B ");
	workerB->moveToThread(threadB);

	connect(threadA, SIGNAL(started()), workerA, SLOT(process()));
	connect(workerA, SIGNAL(finished()), threadA, SLOT(quit()));
	//connect(workerA, SIGNAL(finished()), workerA, SLOT(deleteLater()));
	//connect(threadA, SIGNAL(finished()), threadA, SLOT(deleteLater()));

	connect(threadB, SIGNAL(started()), workerB, SLOT(process()));
	connect(workerB, SIGNAL(finished()), threadB, SLOT(quit()));
	//connect(workerB, SIGNAL(finished()), workerB, SLOT(deleteLater()));
	//connect(threadB, SIGNAL(finished()), threadB, SLOT(deleteLater()));

   connect(threadAButton, SIGNAL(clicked()), this, SLOT(startOrStopThreadA()));
   connect(threadBButton, SIGNAL(clicked()), this, SLOT(startOrStopThreadB()));
   connect(quitButton, SIGNAL(clicked()), this, SLOT(close()));
   .... // displayLayout
}

void ThreadDialog::startOrStopThreadA()
{
   if (threadA->isRunning()) 
   {
       workerA->stop();
       threadAButton->setText(tr("Start A"));
   } 
   else 
   {
	   std::cout << threadA->currentThreadId() << std::endl;
	   workerA->start();
       threadA->start();
       threadAButton->setText(tr("Stop A"));
   }
}

void ThreadDialog::startOrStopThreadB()
{
   if (threadB->isRunning()) 
   {
       workerB->stop();
       threadBButton->setText(tr("Start B"));
   } 
   else 
   {
	   std::cout << threadB->currentThreadId() << std::endl;
	   workerB->start();
       threadB->start();
       threadBButton->setText(tr("Stop B"));
   }
}

void ThreadDialog::closeEvent(QCloseEvent *event)
{
   workerA->stop();
   workerB->stop();
   threadA->wait();
   threadB->wait();
   threadA->exit();
   threadB->exit();

   event->accept();
}

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Please Help me to understand QThread features...
Thank you

GuiHanoi