setDaemon problem.

[Diez B. Roggisch]

Ramashish Baranwal schrieb:
> Hi,
> 
> I am facing an issue in daemonizing a thread using setDaemon method.
> Here is my code-
> 
> import time
> from threading import Thread
> 
> class MThread(Thread):
>     def run(self):
>         f = open('/tmp/t.log', 'w')
>         for i in range(10):
>             f.write('Iteration %d\n' % i)
>             time.sleep(1)
>         f.close()
> 
> if __name__ == "__main__":
>     t = MThread()
>     t.setDaemon(True)
>     print 'Starting thread'
>     t.start()
> 
> The scripts runs all fine, but nothing gets logged to "/tmp/t.log".
> However when I run the same script without setting thread as daemon
> (no call to t.setDaemon), everything works fine.
> 
> Am I missing anything?

Yes. You miss the documentation of setDaemon. It is _not_ a 
PROCESS-daemonization recipe - which you can get here:

http://aspn.activestate.com/ASPN/Cookbook/Python/Recipe/66012

Instead, it means that the thread started is considered not to be worth 
waiting for when the main thread exits. Which it does immediately in 
your code, resulting in nothing written in the logfile.

I think the name setDaemon is somewhat unfortunate.


Diez