subprocess.Popen deadlocks

[eraserix]

Hi

>From time to time I observe a deadlock in subprocess.Popen. I see the
childprocess beeing  and if I attach gdb to the stuck python
script, I can see it waiting on line 1128 in subprocess.py ( data =
_eintr_retry_call(os.read, errpipe_read, 1048576) ).

Any ideas of whats going on? I'm on linux using python 2.6.5. I
already found http://bugs.python.org/issue1731717 and stubbed out
subprocess._cleanup, but this didn't really help and doesn't seem to
be the problem anyway...

A bit of information about what I'm trying to do:
I try to control several process from a python script. Each process is
started from a thread, the threads just wait() for the child to exit
and can then be joined. Main waits for SIGINT. After it received the
signal, it will send a signal to the processes spawned by the threads
and then join() the threads (which should terminate after their
process exits)

Christoph
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Re: subprocess.Popen deadlocks

[eraserix]

On Nov 12, 6:58 am, Lawrence D'Oliveiro  wrote:
> In message
> <2cf9a225-7d1c-4490-8a62-807e79bdd...@n30g2000vbb.googlegroups.com>,
>
> Why not skip all the threads and just spawn all the processes in your main
> loop? Then after getting the SIGINT, send that signal to all your processes,
> and then do a bunch of os.waitpid calls to clean them all up.

Thanks for the hint. You are right, the problem could be solved
singlethreaded by doing some sort of polling (my description
simplified things a bit) avoiding the multithreading problems
altogether.

I had another look at the subprocesses module and discovered the
actual bug. I describe it in issue 10394.

Christoph
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