Beginner: Thread/sleep/Q

ginar

Hi all;
Follow it's my firs program with Thread:
@int main(int argc, char *argv[])
{
QApplication a(argc, argv);
MainWindow w;
w.show();
//--------------------------------
ComQThread COMContex;
COMContex.start();

while(1)
{
    COMContex.write("AlaMaKota"); //do nothing just only write to threads' Queue
}
//--------------------------------

return a.exec&#40;&#41;;

}@

Let's have a look at thread:
@void ComQThread::run(){
QString stringWrite;

while(1)
{
    if(!pQueueWrite->isEmpty())
    {
        stringWrite=pQueueWrite->dequeue();
        qDebug()<<stringWrite;
    }
   msleep(1);
}

}
//-----------

void ComQThread::write(QString string){
pMutex->lock();
pQueueWrite->enqueue(string);
pMutex->unlock();
}

@

//-----------------------------------
The program shall continously prints "AlaMaKota" as intent. But problem is-after a few second after start program crash with:
"The program has unexpectedly finished". If I delete msleep(1) from loop, it cause crash immediately after start.
What the problem?

tchoninho

Hi,

It's a productor/consumer problem... take a look in QSemaphore/QMutex/QWaitCondition examples.

Mario84

Locking the Mutex only when writing (enqueue) isn't enough -> when reading the data (dequeue) you'll have to lock the same Mutex again, to ensure the data is never accessed by both threads at the same time.