[issue5155] Multiprocessing.Queue created by subprocess fails when used in sub-sub-process

[Beau Butler]

New submission from Beau Butler <beau.butler at gmail.com>:

(Note: This issue only happens on linux - on Windows things work fine.)

Please see the attached script.

The script creates a process (TestProcess()). That process runs and
creates a sub-process (TestSubProcess()). When TestSubProcess tries to
access a Queue created by TestProcess, the .get() call fails with the
following stack trace:

Process Process-1:1:
Traceback (most recent call last):
  File "/opt/python2.6/lib/python2.6/multiprocessing/process.py", line
231, in _bootstrap
    self.run()
  File "/opt/python2.6/lib/python2.6/multiprocessing/process.py", line
88, in run
    self._target(*self._args, **self._kwargs)
  File "queue_test.py", line 7, in TestSubProcess
    item = q.get()                        # Fails with IOError if queue
created in TestProcess
  File "/opt/python2.6/lib/python2.6/multiprocessing/queues.py", line
91, in get
    res = self._recv()
IOError: [Errno 9] Bad file descriptor

If the same queue is created by main (top level), TestSubProcess
accesses it with no errors. This behavior can be stimulated by
uncommenting the q = multiprocessing.Queue() line in TestProcess.


Tested using:
Python 2.6.1 (r261:67517, Dec  4 2008, 16:51:00) [MSC v.1500 32 bit
(Intel)] on win32
(Installed using binary installer, windows XPSP2)

*No problems*

Python 2.6.1 (r261:67515, Jan  6 2009, 15:23:19) [GCC 4.2.4 (Ubuntu
4.2.4-1ubuntu3)] on linux2
(Compiled from source due to ubuntu 8.04 (Hardy) not having python2.6 yet)

*Fails on q.get() in TestSubProcess*

----------
components: Library (Lib)
files: queue_test.py
messages: 81183
nosy: bbutler
severity: normal
status: open
title: Multiprocessing.Queue created by subprocess fails when used in sub-sub-process
type: crash
versions: Python 2.6
Added file: http://bugs.python.org/file12944/queue_test.py

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Python tracker <report at bugs.python.org>
<http://bugs.python.org/issue5155>
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