(original) (raw)

changeset: 77020:565734c9b66d parent: 77018:364289cc7891 user: Antoine Pitrou solipsis@pitrou.net date: Fri May 18 13:57:04 2012 +0200 files: Doc/library/multiprocessing.rst Doc/library/threading.rst description: Remove outdated statements about threading and imports. diff -r 364289cc7891 -r 565734c9b66d Doc/library/multiprocessing.rst --- a/Doc/library/multiprocessing.rst Thu May 17 21:13:45 2012 +0200 +++ b/Doc/library/multiprocessing.rst Fri May 18 13:57:04 2012 +0200 @@ -120,9 +120,7 @@ print(q.get()) # prints "[42, None, 'hello']" p.join() - Queues are thread and process safe, but note that they must never - be instantiated as a side effect of importing a module: this can lead - to a deadlock! (see :ref:`threaded-imports`) + Queues are thread and process safe. **Pipes** diff -r 364289cc7891 -r 565734c9b66d Doc/library/threading.rst --- a/Doc/library/threading.rst Thu May 17 21:13:45 2012 +0200 +++ b/Doc/library/threading.rst Fri May 18 13:57:04 2012 +0200 @@ -996,27 +996,3 @@ Currently, :class:`Lock`, :class:`RLock`, :class:`Condition`, :class:`Semaphore`, and :class:`BoundedSemaphore` objects may be used as :keyword:`with` statement context managers. - - -.. _threaded-imports: - -Importing in threaded code --------------------------- - -While the import machinery is thread-safe, there are two key restrictions on -threaded imports due to inherent limitations in the way that thread-safety is -provided: - -* Firstly, other than in the main module, an import should not have the - side effect of spawning a new thread and then waiting for that thread in - any way. Failing to abide by this restriction can lead to a deadlock if - the spawned thread directly or indirectly attempts to import a module. -* Secondly, all import attempts must be completed before the interpreter - starts shutting itself down. This can be most easily achieved by only - performing imports from non-daemon threads created through the threading - module. Daemon threads and threads created directly with the thread - module will require some other form of synchronization to ensure they do - not attempt imports after system shutdown has commenced. Failure to - abide by this restriction will lead to intermittent exceptions and - crashes during interpreter shutdown (as the late imports attempt to - access machinery which is no longer in a valid state). /solipsis@pitrou.net