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From: Christian Heimes <lists@cheimes.de>
Subject: Re: Multiple threads
Date: Wed, 16 Nov 2011 16:01:15 +0100
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Xref: x330-a1.tempe.blueboxinc.net comp.lang.python:15776

Am 16.11.2011 14:48, schrieb Eduardo Oliva:
> Hello, I have a py script that reads for all "m2ts" video files and convert them to "mpeg" using ffmpeg with command line.
> 
> What I want to do is:
> 
>   I need my script to run 2 separated threads, and then when the first has finished, starts the next one....but no more than 2 threads.
>   I know that Semaphores would help with that.
>   But the problem here is to know when the thread has finished its job, to release the semaphore and start another thread.

I suggest a slight different approach: use a queue [1] and create two
worker threads that consume the queue. You don't need multiprocessing
because you are already using multiple processes here (one Python and
two ffmpeg processes).

Christian

[1] http://docs.python.org/library/queue.html