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gh-85299: Add note warning about entry point guard for asyncio example #93457

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merged 5 commits into from
Oct 16, 2022
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gh-85299: Add note warning about entry point guard for asyncio example #93457

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97d022e
Add note warning about entry point guard for asyncio example
slateny Jun 3, 2022
16cb255
Add entry guard, clarify note on platform
slateny Oct 15, 2022
0129bdf
Add ref target in multiprocessing
slateny Oct 16, 2022
fd68a5e
Use rewording for multiprocessing
slateny Oct 16, 2022
8ba4b0c
Add missing grave sign
slateny Oct 16, 2022
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6 changes: 6 additions & 0 deletions Doc/library/asyncio-eventloop.rst
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Expand Up @@ -1208,6 +1208,12 @@ Executing code in thread or process pools

asyncio.run(main())

Note that on macOS, an entry point guard may be needed as the example would
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@kumaraditya303 kumaraditya303 Oct 13, 2022

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It would be better to just add __name__ == '__main__'. This happens on Windows too not just macOS.

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@gvanrossum gvanrossum Oct 13, 2022

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Exactly.

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@slateny slateny Oct 14, 2022

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That's a good point, Windows also defaults to spawn so looks like it runs into the same issue as mac. Should this note still remain as an fyi, or just change the example to fix the problem and leave out the note? It's customary to have the guard in general but knowing why it fails without might still be helpful, but I don't feel too strongly either way.

otherwise cause a :exc:`RuntimeError`. See the `Changed in version 3.8 note
<https://docs.python.org/3/library/multiprocessing.html#contexts-and-start-methods>`_
and `Safe importing of main module
<https://docs.python.org/3/library/multiprocessing.html#the-spawn-and-forkserver-start-methods>`_.

This method returns a :class:`asyncio.Future` object.

Use :func:`functools.partial` :ref:`to pass keyword arguments
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