Cannot import name SemLock in Lucid

[David Coconut]

Binary package hint: python3.1

Ubuntu 10.04 Lucid Lynx Beta 2, AMD-64
Linux kernel 2.6.32.19-generic

Ubuntu 10.04 Lucid Lynx Beta 2, x86
Linux kernel 2.6.32.16-generic

Latest version of Python 3.1.2 in Lucid repositories on both systems.

When using the multiprocessing module, the below error is returned, specifically when trying to create a new JoinableQueue. This should not happen.

Created a Python bug report but initial responses indicate this may be a problem with Lucid's packaging. The code worked flawlessly on Karmic Koala.

----

Traceback (most recent call last):

File "/usr/lib/python3.1/multiprocessing/synchronize.py", line 28, in <module> from _multiprocessing import SemLock
ImportError: cannot import name SemLock

During handling of the above exception, another exception occurred:

Traceback (most recent call last):
File "main.py", line 16, in <module>
q = JoinableQueue()

File "/usr/lib/python3.1/multiprocessing/__init__.py", line 218, in JoinableQueue from multiprocessing.queues import JoinableQueue
File "/usr/lib/python3.1/multiprocessing/queues.py", line 22, in <module> from multiprocessing.synchronize import Lock, BoundedSemaphore, Semaphore, Condition
File "/usr/lib/python3.1/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.

[Matthias Klose (doko)]

these tests fail on the buildds ...

checking whether POSIX semaphores are enabled... no
checking for broken sem_getvalue... yes

#include <unistd.h>
#include <fcntl.h>
#include <stdio.h>
#include <semaphore.h>
#include <sys/stat.h>

int main(void) {
  sem_t *a = sem_open("/autoconf", O_CREAT, S_IRUSR|S_IWUSR, 0);
  if (a == SEM_FAILED) {
    perror("sem_open");
    return 1;
  }
  sem_close(a);
  sem_unlink("/autoconf");
  return 0;
}

[Matthias Klose (doko)]

sem_open: Function not implemented
1
$ uname -a
Linux ronne 2.6.24-25-server #1 SMP Tue Oct 20 07:20:02 UTC 2009 i686 GNU/Linux

the buildds are running hardy kernels

[Matthias Klose (doko)]

caused by introducing a configure check in 3.1.2, regression compared to karmic. will work around it

[Launchpad Janitor (janitor)]

This bug was fixed in the package python3.1 - 3.1.2-0ubuntu2

---------------
python3.1 (3.1.2-0ubuntu2) lucid; urgency=low

  * Overwrite the sem_open autoconf check, depending on a newer
    kernel version not available on the buildd. LP: #556477.
  * debian/patches/issue8032.dpatch: Update to version from the
    trunk. Upload for beta2 to avoid apport errors.
    - Handle PyFrameObject's: LP: #543624, #548723.
    - Detect cycles in object reference graph and add extra
      protection: LP: #544823, LP: #552356.
 -- Matthias Klose <email address hidden> Wed, 14 Apr 2010 23:54:59 +0200