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Diffstat (limited to 'Doc/library/concurrent.futures.rst')
| -rw-r--r-- | Doc/library/concurrent.futures.rst | 12 |
1 files changed, 11 insertions, 1 deletions
diff --git a/Doc/library/concurrent.futures.rst b/Doc/library/concurrent.futures.rst index 0495737..e487817 100644 --- a/Doc/library/concurrent.futures.rst +++ b/Doc/library/concurrent.futures.rst @@ -115,11 +115,19 @@ And:: executor.submit(wait_on_future) -.. class:: ThreadPoolExecutor(max_workers) +.. class:: ThreadPoolExecutor(max_workers=None) An :class:`Executor` subclass that uses a pool of at most *max_workers* threads to execute calls asynchronously. + .. versionchanged:: 3.5 + If *max_workers* is ``None`` or + not given, it will default to the number of processors on the machine, + multiplied by ``5``, assuming that :class:`ThreadPoolExecutor` is often + used to overlap I/O instead of CPU work and the number of workers + should be higher than the number of workers + for :class:`ProcessPoolExecutor`. + .. _threadpoolexecutor-example: @@ -175,6 +183,8 @@ to a :class:`ProcessPoolExecutor` will result in deadlock. An :class:`Executor` subclass that executes calls asynchronously using a pool of at most *max_workers* processes. If *max_workers* is ``None`` or not given, it will default to the number of processors on the machine. + If *max_workers* is lower or equal to ``0``, then a :exc:`ValueError` + will be raised. .. versionchanged:: 3.3 When one of the worker processes terminates abruptly, a |