Why is it that, for the code below, the Thread1.printEvent() gets printed as often as Thread2.printEvent()? My thought is that since it's 2 separate event loops (due to 2 threads), Thread1.printEvent() should keep on going even though Thread2.printEvent() takes a long time?

Here's how everything is connected:

--> denotes is connected to

Thread1.timer.timeout() --> Thread1.doSomething(); // times out every 1 second
Thread1.doSomething() --> Thread1.printEvent(); // takes "zero" time
Thread1.doSomething() --> Thread2.printEvent(); // takes 10 seconds


This is the code for Thread1
Qt Code: 
  1. #include <QThread>
  2. #include <QTimer>
  3.  
  4. class Thread1 : public QThread
  5. {
  6.   Q_OBJECT
  7.  
  8. public:
  9.   void run();
  10.  
  11. private:
  12.   QTimer*   timer;
  13.  
  14. signals:
  15.   void doSomething();
  16.  
  17. private slots:
  18.   void printEvent();
  19.  
  20. private:
  21.   int number; 
  22. };
  23.  
  24. #include <iostream>
  25.  
  26. void Thread1::run()
  27. {
  28.   number = 0;
  29.  
  30.   // We create QTimer here because it has thread-affinity
  31.   timer = new QTimer();
  32.   if(!QObject::connect( timer,
  33.                     SIGNAL(timeout()),
  34.                     this,
  35.                     SIGNAL(doSomething())))
  36.   {
  37.     throw std::runtime_error( "ERROR!" );
  38.   }
  39.   if(!QObject::connect( this,
  40.     SIGNAL(doSomething()),
  41.     this,
  42.     SLOT(printEvent())))
  43.   {
  44.     throw std::runtime_error( "ERROR!" );
  45.   }
  46.  
  47.   timer->start(1000);
  48.   this->exec();
  49.  
  50.   delete timer;
  51. }
  52.  
  53. void Thread1::printEvent()
  54. {
  55.   std::cout << "Thread1: sending event... " << number++ << std::endl;
  56. }
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This is the code for Thread2..
Qt Code: 
  1. #include <QThread>
  2.  
  3. class Thread2 : public QThread
  4. {
  5.   Q_OBJECT
  6.  
  7. public:
  8.   void run();
  9.  
  10. public slots:
  11.   void  printEvent();
  12.  
  13. private:
  14.   int number;
  15. };
  16.  
  17. #include <iostream>
  18.  
  19. void Thread2::run()
  20. {
  21.   number = 0;
  22.   exec();
  23. }
  24.  
  25. void Thread2::printEvent()
  26. {
  27.   std::cout << "Thread2: Received event... " << number++ << std::endl;
  28.   if( number < 3 )
  29.   {
  30.     msleep(10000);
  31.   }
  32. }
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Lastly, this is the code for main.cpp
Qt Code: 
  1. #include <QObject>
  2. #include <QtCore/QCoreApplication>
  3.  
  4. int main( int   argc,
  5.           char* argv[] )
  6. {
  8.                        argv );
  9.  
  10.   Thread1           thread1;
  11.   Thread2           thread2;
  12.  
  13.   // Connect the 2 threads signal slot here
  14.   if (!QObject::connect(&thread1, SIGNAL(doSomething()),
  15.       &thread2, SLOT(printEvent())))
  16.   {
  17.     throw std::runtime_error( "ERROR!" );
  18.   }
  19.  
  20.   thread1.start();
  21.   thread2.start();
  22.  
  23.   return a.exec();
  24. }
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