https://github.com/python/cpython/commit/b5805892d55e769335c11a994b586355720263ba
commit: b5805892d55e769335c11a994b586355720263ba
branch: main
author: Ulrik Södergren <[email protected]>
committer: gpshead <[email protected]>
date: 2024-07-13T13:07:40-07:00
summary:
gh-73159 Added clarifications in multiprocessing docs on that objects are
pickled. (GH-121686)
Added explicit comments about that objects are pickled when transmitted via
multiprocessing queues and pipes.
files:
M Doc/library/multiprocessing.rst
diff --git a/Doc/library/multiprocessing.rst b/Doc/library/multiprocessing.rst
index 426291c5f0743d..bc615b8e297046 100644
--- a/Doc/library/multiprocessing.rst
+++ b/Doc/library/multiprocessing.rst
@@ -254,6 +254,7 @@ processes:
p.join()
Queues are thread and process safe.
+ Any object put into a :mod:`~multiprocessing` queue will be serialized.
**Pipes**
@@ -281,6 +282,8 @@ processes:
of corruption from processes using different ends of the pipe at the same
time.
+ The :meth:`~Connection.send` method serializes the the object and
+ :meth:`~Connection.recv` re-creates the object.
Synchronization between processes
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
@@ -745,6 +748,11 @@ If you use :class:`JoinableQueue` then you **must** call
semaphore used to count the number of unfinished tasks may eventually overflow,
raising an exception.
+One difference from other Python queue implementations, is that
:mod:`multiprocessing`
+queues serializes all objects that are put into them using :mod:`pickle`.
+The object return by the get method is a re-created object that does not share
memory
+with the original object.
+
Note that one can also create a shared queue by using a manager object -- see
:ref:`multiprocessing-managers`.
@@ -811,6 +819,8 @@ For an example of the usage of queues for interprocess
communication see
used for receiving messages and ``conn2`` can only be used for sending
messages.
+ The :meth:`~multiprocessing.Connection.send` method serializes the the
object using
+ :mod:`pickle` and the :meth:`~multiprocessing.Connection.recv` re-creates
the object.
.. class:: Queue([maxsize])
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