Qt QApplication::processEvents() in custom event handler

Question

Is it possible to call QApplication::processEvents() inside the event handler, where there is a long process. My program terminates with Segfault. My code is something like this:

void MyApplication::customEvent(QEvent* event)
{
  if(event->type() == UserEventCustom)
  {
    for(int i = 0; i < 99999; ++i)
    {
       QApplication::processEvents();
       doSomething();
    }

    event->accept();
  }
}

You should post a complete example, this part of code doesn't show any problem. — ismail, Dec 30 '10 at 08:38
Is it unclear from the dump where exactly in Qt (not QT by the way) it happens and why? Could be an unrelated bug in Qt, calling processEvents() by itself is fine, it doesn't seem to be a problem here. — Sergei Tachenov, Dec 30 '10 at 14:11
I suspect a stack overflow, which might be resolved by moving `event->accept()` in front of the busy loop... — Ton van den Heuvel, Dec 31 '10 at 16:37

score 1 · Answer 1 · answered May 11 '11 at 04:14

I suspect that Ton van den Heuvel (from comments) is correct that you are seeing a stack overflow.

However, at my company, we have found it best to avoid processEvents(). Our experience has shown processEvents() to cause crashes and we try to avoid its use. I would ask yourself whether you could refactor your code to do without the processEvents() call. For example, you might spawn a thread to do you processing.

Qt QApplication::processEvents() in custom event handler

1 Answers1