fork, threads and proper closing

Francesco Bochicchio bieffe62 at gmail.com
Mon Jun 29 14:44:27 CEST 2009


On 29 Giu, 07:10, OdarR <Olivier.Da... at gmail.com> wrote:
> On 28 juin, 23:26, Tomasz Pajor <ni... at puffy.pl> wrote:
>
> > Hello,
>
> > Configuration is as follows.
>
> > I have a starter process which creates 3 sub processes (forks) and each
> > of this processes creates a number of threads.
> > Threads in that processes have semaphore so on KeyboardInterrupt without
> > sending a sigterm to the subprocess i'm not able to close threads.
> > Is there any work around? Can I somehow run join for the thread on
> > keyboard interrupt?
>
> When creating a thread you can add a Queue parameter to communicate
> with threads:http://docs.python.org/library/queue.html
> easy and reliable.
>
> give them a "poison pill" in the queue: a recognizable object placed
> on the queue that means "when you get this, stop."
>

This is the way I usually go, but it has one important limitation: if
the thread is waiting
for a blocking I/O operation to complete, like reading from a socket
with no data or waiting
for a locked resource (i.e. semaphore) to be unlocked, it will not
service the queue and will
not read the 'quit command' (the poison pill), and therefore will not
quit until the blocking
I/O terminates (and it could be never).

ASAIK, there is no way - in python - to solve this.



> Olivier

Ciao
----
FB




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