bpo-38501: Add a warning section to multiprocessing.Pool docs about resource managing (GH-19466)

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Pablo Galindo 2020-04-11 03:05:37 +01:00 committed by GitHub
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@ -439,7 +439,8 @@ process which created it.
>>> def f(x):
... return x*x
...
>>> p.map(f, [1,2,3])
>>> with p:
... p.map(f, [1,2,3])
Process PoolWorker-1:
Process PoolWorker-2:
Process PoolWorker-3:
@ -2127,6 +2128,16 @@ with the :class:`Pool` class.
Note that the methods of the pool object should only be called by
the process which created the pool.
.. warning::
:class:`multiprocessing.pool` objects have internal resources that need to be
properly managed (like any other resource) by using the pool as a context manager
or by calling :meth:`close` and :meth:`terminate` manually. Failure to do this
can lead to the process hanging on finalization.
Note that is **not correct** to rely on the garbage colletor to destroy the pool
as CPython does not assure that the finalizer of the pool will be called
(see :meth:`object.__del__` for more information).
.. versionadded:: 3.2
*maxtasksperchild*