Davin Potts added the comment:
Attaching patches for 3.5/default, 3.4, and 2.7 which update the documentation
on multiprocessing.Lock, RLock, Semaphore, and BoundedSemaphore to describe
their actual implemented behavior, replacing the existing, misleading claim
that they are clones of threading.Lock, etc., respectively.
Specific changes:
* Lock and RLock now have their acquire and release methods drawn out so as to
best explain the significant behavioral differences (versus threading) in
return values, potential exceptions being raised, and passing arguments.
* Semaphore and BoundedSemaphore are not as drawn out because their behaviors
are indeed the same in every regard except for the difference in
block-vs-blocking (and in the case of 2.7, timeout is novel in multiprocessing
and doesn't appear until 3.2 in threading).
* In 3.4 and 3.5, the inaccurate note block at the end of the synchronization
section no longer misrepresents the treatment of the timeout argument in
threading analogs.
It is worth noting that in 3.x, the behavior around the timeout argument in
multiprocessing.{Lock,RLock,Semaphore,BoundedSemaphore} already matches that of
threading.Semaphore and BoundedSemaphore. The threading module appears
inconsistent in its use of the timeout argument when comparing
Semaphore/BoundedSemaphore with Lock/RLock. It would be interesting to
investigate whether in 3.x this inconsistency within threading could be brought
in line with the rest of multiprocessing.
In issue21342 the notion of unifying the implementations of these
synchronization primitives across threading and multiprocessing is suggested.
If that is pursued, it would reasonably be attempted on default/3.5 and not
backported to 2.7 (nor probably 3.4). Thus this patch to update the
documentation is still highly valuable for 2.7 and 3.4 and 3.5 (at least until
such time as a unification effort might be undertaken in the case of 3.5).
----------
keywords: +patch
stage: needs patch -> patch review
Added file:
http://bugs.python.org/file38702/issue_23484_doc_locks_py35_and_py34.patch
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