Threads in PyQt4

I want to create threads in PyQt4 (for normal use GUI).

Make thread class:

class solveThread(QtCore.QThread):
        def run(self):
              <what do you want doing>

Check for use thread with same name and kill it if yes:

        if (hasattr(self,'s1')):
            del(self.s1)
        self.s1=solveThread()


If I want terminate thread by button, I use variable self.isExit=0 in infinite while loop (I don't use Thread.terminate() ). And I use refresh GUI each 5-10 sec (otherwise my GIU is freezing).