Description Jan Beich 2013-05-02 20:40:01 UTC

python27 is always built with multiprocessing support on >= 9.0 or
on 7.1..8.4 with sem.ko preloaded because autoconf finds working
sem_open(). And python2[67] always USE_SEMAPHORES for locking which
seems to work fine with libthr's sem_init(pshared=0).

Fix: Just an incomplete attempt to make SEM more predictable:

  - remove checks for EOL releases
  - limit sem.ko warning and extra patches to 8.x users
  - warn 9.x users semaphores support cannot be disabled like in python3x
  - rely on autoconf to find sem_open et al. like netbsd or python3x
  - enable sem_open for python26 on >= 9.0 by default like python27
  - don't use semaphores for locking if SEM is unset on 8.x
How-To-Repeat: FreeBSD 9.0 or later:

$ python3.3 -c 'import multiprocessing.synchronize'
$ python2.7 -c 'import multiprocessing.synchronize'
$ python2.6 -c 'import multiprocessing.synchronize'
Traceback (most recent call last):
  File "<string>", line 1, in <module>
  File "/usr/local/lib/python2.6/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.

FreeBSD 7.2..8.4:

$ python3.3 -c 'import multiprocessing.synchronize'
Traceback (most recent call last):
  File "/usr/local/lib/python3.3/multiprocessing/synchronize.py", line 27, 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 "<string>", line 1, in <module>
  File "/usr/local/lib/python3.3/multiprocessing/synchronize.py", line 32, 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.

$ python2.7 -c 'import multiprocessing.synchronize'
Traceback (most recent call last):
  File "<string>", line 1, in <module>
  File "/usr/local/lib/python2.7/multiprocessing/synchronize.py", line 59, 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.

$ python2.6 -c 'import multiprocessing.synchronize'
Traceback (most recent call last):
  File "<string>", line 1, in <module>
  File "/usr/local/lib/python2.6/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.