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Issue #6963: Added maxtasksperchild argument to multiprocessing.Pool

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Jesse Noller 2010-01-27 03:05:57 +00:00
parent 2deb5c758a
commit 654ade3e6a
6 changed files with 130 additions and 19 deletions
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17
Doc/library/multiprocessing.rst
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@ -1537,7 +1537,7 @@ Process Pools
One can create a pool of processes which will carry out tasks submitted to it
with the :class:`Pool` class.
.. class:: multiprocessing.Pool([processes[, initializer[, initargs]]])
.. class:: multiprocessing.Pool([processes[, initializer[, initargs[, maxtasksperchild]]]])
A process pool object which controls a pool of worker processes to which jobs
can be submitted. It supports asynchronous results with timeouts and
@ -1548,6 +1548,21 @@ with the :class:`Pool` class.
*initializer* is not ``None`` then each worker process will call
``initializer(*initargs)`` when it starts.
*maxtasksperchild* is the number of tasks a worker process can complete
before it will exit and be replaced with a fresh worker process, to enable
unused resources to be freed. The default *maxtasksperchild* is None, which
means worker processes will live as long as the pool.
.. note::
Worker processes within a :class:`Pool` typically live for the complete
duration of the Pool's work queue. A frequent pattern found in other
systems (such as Apache, mod_wsgi, etc) to free resources held by
workers is to allow a worker within a pool to complete only a set
amount of work before being exiting, being cleaned up and a new
process spawned to replace the old one. The *maxtasksperchild*
argument to the :class:`Pool` exposes this ability to the end user.
.. method:: apply(func[, args[, kwds]])
Equivalent of the :func:`apply` built-in function. It blocks till the