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Message-ID: <43F9BEDE.8070501@mit.edu>
Date: Mon, 20 Feb 2006 08:06:38 -0500
From: Steve Ward <ward AT mit DOT edu>
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To: Steve Ward <ward AT mit DOT edu>
CC: cygwin AT cygwin DOT com
Subject: Re: Python Tkinter after method silently exits
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I should have mentioned: I'm using python 2.4.1 (the
current cygwin distribution) in both cases.  The test
program fails with a current, up-to-date cygwin setup;
downgrading ONLY cygwin1.dll to 1.5.18-1 causes it to
work, suggesting that the problem is with cygwin1.dll
rather than with python.

- Steve Ward


Steve Ward wrote:
> 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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