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Date:	Mon, 20 Feb 2006 07:41:40 -0500
From:	Steve Ward <ward AT mit DOT edu>
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To:	cygwin AT cygwin DOT com
Subject:	Python Tkinter after method silently exits
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On upgrading to the latest 1.5.19-4 cygwin release, I
find that several previously working python programs
began mysteriously exiting.  I've boiled the problem
down to a skeletal test program (attached), which runs
under the prior 1.5.18-1 release but exits under 1.5.19-4.

The second thread seems necessary to stimulate the failure;
even commenting out the sleep(100) to make it return
immediately avoides the spurious exit.  When the second
thread is running, the self.root.after(...) call
apparently causes a silent exit rather than returning.

Any help/ideas would be appreciated...

- Steve Ward


# Demonstrate python/Tkinter threading bug

class App:

     def __init__(self, root):

         self.root = root
         self.update_loop()

         # Start a second thread, to do whatever...
         self.thread = threading.Thread(target=self.second_thread)
         self.thread.start()

     def update_loop(self):
         print >>sys.stderr, "*** update_loop"
         self.root.after(400, self.update_loop)

     def second_thread(self):
         sleep(100)

if __name__ == "__main__":
     root = TK.Tk()
     app = App(root)
     root.mainloop();

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