Doubts related to subprocess.Popen()

srinivasan srinivas sri_annauni at
Tue Jan 20 15:19:33 CET 2009

Do parent process will have different file descriptor in it for each subprocesses or paprent uses a single file descriptor for all?
I really want to know creation of each subprocess will occupy an entry in parents'file descriptor table. B'cos if i create more than 200 subprocesses, i am getting 'Too many open files' error.

----- Original Message ----
From: Mark Wooding <mdw at>
To: python-list at
Sent: Tuesday, 20 January, 2009 6:16:17 PM
Subject: Re: Doubts related to subprocess.Popen()

srinivasan srinivas <sri_annauni at> writes:

> Does subprocess.Popen() count a new open file for each suprocess? I
> mean does it occupy an entry in file descriptor table of parent
> process?  If so, wat is each file descriptor connected to?

On Unix, subprocess.Popen will use up a file descriptor in the parent
for each use of subprocess.PIPE.  The descriptor in question is one end
of a pipe; the child process holds the other end.

I guess the situation is similar on Windows, but I don't know for sure.

-- [mdw]

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