[Bug 672209] Re: [SRU] multiprocessing module dysfunctional

[Barry Warsaw]

I had to enable /dev/shm mounting in my chroots.  E.g. from
schroot/default/fstab:


=== modified file 'schroot/default/fstab'
--- schroot/default/fstab	2011-07-13 20:34:15 +0000
+++ schroot/default/fstab	2011-08-22 18:56:00 +0000
@@ -16,8 +16,8 @@
 # killing services on the host.
 #/run		/run		none	rw,bind		0	0
 #/run/lock	/run/lock	none	rw,bind		0	0
-#/dev/shm	/dev/shm	none	rw,bind		0	0
-#/run/shm	/run/shm	none	rw,bind		0	0
+/dev/shm	/dev/shm	none	rw,bind		0	0
+/run/shm	/run/shm	none	rw,bind		0	0
 
 # Additions according to
 # https://wiki.ubuntu.com/SecurityTeam/BuildEnvironment

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https://bugs.launchpad.net/bugs/672209

Title:
  [SRU] multiprocessing module dysfunctional

Status in “python2.7” package in Ubuntu:
  Fix Released
Status in “python2.7” source package in Maverick:
  Fix Committed

Bug description:
  * Impact of bug: This bug will prevent common usage of the multiprocessing module in Python 2.7 on Maverick.
  * Fix: The bug was addressed in the current version of Ubuntu with a no-change rebuild. Since the original problem was caused by kernel configuration on the buildd's, and (as verified by PPA build) this has been rectified, a simple rebuild is all that's needed
  * TEST CASE: see above or: $ python2.7 -c 'from _multiprocessing import SemLock'
  * I don't see much chance for regression. Code which relies on multiprocessing in Python 2.7 can't currently run on Maverick. This rebuild will only re-enable standard Python functionality.
  Binary package hint: python2.7

  On Maverick with python2.7 (2.7-6 deb version), the multiprocessing
  module fails to operate:

  python2.7 -c 'import multiprocessing; multiprocessing.Pool()'
  Traceback (most recent call last):
    File "<string>", line 1, in <module>
    File "/usr/lib/python2.7/multiprocessing/__init__.py", line 227, in Pool
      return Pool(processes, initializer, initargs, maxtasksperchild)
    File "/usr/lib/python2.7/multiprocessing/pool.py", line 89, in __init__
      self._setup_queues()
    File "/usr/lib/python2.7/multiprocessing/pool.py", line 181, in _setup_queues
      from .queues import SimpleQueue
    File "/usr/lib/python2.7/multiprocessing/queues.py", line 22, in <module>
      from multiprocessing.synchronize import Lock, BoundedSemaphore, Semaphore, Condition
    File "/usr/lib/python2.7/multiprocessing/synchronize.py", line 33, in <module>
      " function, see issue 3770.")
  ImportError: This platform lacks a functioning sem_open implementation, therefore, the required synchronization primitives needed will not function, see issue 3770.

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