[Python-Dev] [Python-checkins] cpython: Remove outdated statements about threading and imports.

[Nick Coghlan]

I know you fixed the deadlock problem, but the warnings about shutdown
misbehaviour are still valid.

--
Sent from my phone, thus the relative brevity :)
On May 18, 2012 9:59 PM, "antoine.pitrou" <python-checkins at python.org>
wrote:

> http://hg.python.org/cpython/rev/565734c9b66d
> changeset:   77020:565734c9b66d
> parent:      77018:364289cc7891
> user:        Antoine Pitrou <solipsis at pitrou.net>
> date:        Fri May 18 13:57:04 2012 +0200
> summary:
>  Remove outdated statements about threading and imports.
>
> files:
>  Doc/library/multiprocessing.rst |   4 +--
>  Doc/library/threading.rst       |  23 ---------------------
>  2 files changed, 1 insertions(+), 26 deletions(-)
>
>
> diff --git a/Doc/library/multiprocessing.rst
> b/Doc/library/multiprocessing.rst
> --- a/Doc/library/multiprocessing.rst
> +++ b/Doc/library/multiprocessing.rst
> @@ -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 --git a/Doc/library/threading.rst b/Doc/library/threading.rst
> --- a/Doc/library/threading.rst
> +++ b/Doc/library/threading.rst
> @@ -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).
>
> --
> Repository URL: http://hg.python.org/cpython
>
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