Quote Originally Posted by soumyadeep_pan View Post
What do you mean by a main thread ?
The main thread (a.k.a. the GUI thread) is the one that created the QApplication instance.

Quote Originally Posted by soumyadeep_pan View Post
Can I do any semaphore post to that thread ?
Typical way of communication between worker threads and the GUI thread is to use custom events. QApplication provides some locking mechanism, but custom events are better.