[Pyobjc-dev] Not calling 'finally'

[Bob S. <rsw...@tr...>]

We have a Cocoa-based product using PyObjC that starts up some background
processes.  When the application quits, we want to stop them.  As long as
there are no errors, everything works fine - we create the processes in
applicationDidFinishLaunching_ and kill them in applicationWillTerminate_

However, I noticed while debugging that if I got a python error that stopped
the main process that the daemons would keep on running.
applicationWillTerminate_ must not have been called.  So, I decided to add a
try/finally block in the main code:

if __name__ == '__main__:
    try:
        AppHelper.runEventLoop()
    finally:
        MyController.stopDaemons()

where MyController.stopDaemons() is a staticmethod that stops the background
processes.  However, I put print statements into stopDaemons and find that
while it is called properly in applicationWillTerminate_, it does not seem
to be called in the finally block when I quit the application.

It is possible that quitting calls os._exit which according to Python in a
Nutshell (p 274) does not invoke clean-up handlers.  I'm not sure if this is
the case, or if print cannot be called when the application is terminating.

Is such a try/finally construct useful here?  How do I ensure proper cleanup
even on abnormal termination?

Thanks for your help,

Bob Swerdlow
COO
Transpose
rsw...@tr...
207-781-8284
http://www.transpose.com

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