[Python-bugs-list] [ python-Bugs-761888 ] popen2.Popen3 and popen2.Popen4 leaks filedescriptors

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Bugs item #761888, was opened at 2003-06-27 10:58
Message generated for change (Comment added) made by nnorwitz
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Category: Python Library
Group: Python 2.3
Status: Open
Resolution: None
Priority: 5
Submitted By: Troels Walsted Hansen (troels)
>Assigned to: Guido van Rossum (gvanrossum)
Summary: popen2.Popen3 and popen2.Popen4 leaks filedescriptors

Initial Comment:
The code below (from Lib/popen2.py) appears to leak no
less then 4 filedescriptors if os.fork() raises an
exception (say "OSError: [Errno 12] Not enough space"
on a Solaris box running out of swap).

Popen3.__init__() appears to leak 6 filedescriptors.

class Popen4(Popen3):
    def __init__(self, cmd, bufsize=-1):
        p2cread, p2cwrite = os.pipe()
        c2pread, c2pwrite = os.pipe()
        self.pid = os.fork()


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>Comment By: Neal Norwitz (nnorwitz)
Date: 2003-06-30 23:40

Message:
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I tried to make it easier to review the patches by providing
2.  They were wrong though.  It was still possible to leak
file descriptors.  I believe the new patch 3 should not
allow any file descriptors to leak.

This solution is really ugly, but I can't come up with
anything cleaner.  I tried having a list of the fds that
need to be closed, but it really isn't any better.

Would it be possible (in 2.4) to make an fd type which
derives from int, so that the fd can be closed on deallocation?

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Comment By: Guido van Rossum (gvanrossum)
Date: 2003-06-30 11:57

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I haven't reviewed the code or the fix, but as a bugfix this
could go into 2.3.

The two patch files are confusing -- why two?

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Comment By: Neal Norwitz (nnorwitz)
Date: 2003-06-28 23:10

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Tim, for 2.3b2 or 2.3.1?

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Comment By: Neal Norwitz (nnorwitz)
Date: 2003-06-28 23:09

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The attached patch should fix the problem, I'd appreciate if
you could test this.  There are 2 files attached, one is a
context diff with whitespace modifications, the other is a
minimal (no whitespace differences) patch to show what's
changed (ie, the try/except).

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