Description

hroncok

opened on Mar 12, 2025

Issue body actions

Bug report

Bug description:

from asyncio.events import BaseDefaultEventLoopPolicy

This is from https://github.com/MagicStack/uvloop/blob/7bb12a174884b2ec8b3162a08564e5fb8a5c6b39/uvloop/__init__.py#L6 cc @fantix

On Python 3.13, this works.
On Python 3.14 since #128216 this no longer works and raises ImportError. As far as I know, the class was not deprecated in 3.13 or 3.12.

>>> from asyncio.events import BaseDefaultEventLoopPolicy
Traceback (most recent call last):
  File "<python-input-0>", line 1, in <module>
    from asyncio.events import BaseDefaultEventLoopPolicy
ImportError: cannot import name 'BaseDefaultEventLoopPolicy' from 'asyncio.events' (/usr/lib64/python3.14/asyncio/events.py)

The commit message of #128216 does not mention any API removals at all. It has no NEWS either, so I assume this removal was accidental.

CPython versions tested on:

3.14, CPython main branch

Operating systems tested on:

Linux

Activity

1. hroncok

   added

   type-bugAn unexpected behavior, bug, or errorAn unexpected behavior, bug, or error

   on Mar 12, 2025
2. hroncok

   added a commit that references this issue on Mar 12, 2025

   Workaround missing BaseDefaultEventLoopPolicy in Python 3.14

   9e6c20a
3. picnixz commented on Mar 12, 2025

   

   picnixz

   on Mar 12, 2025

   Member

   More actions

   I'm not sure this was meant to actually be publicly exposed. Policies were deprecated since 3.12 and asyncio.events.BaseDefaultEventLoopPolicy has probably not been intended to be public (I can't find it documented anywhere). cc @kumaraditya303

   Note that it's not really gone, just that it has been now named as really "private" (but maybe it should have been kept half-public?)
4. picnixz

   added

   topic-asyncio

   stdlibStandard Library Python modules in the Lib/ directoryStandard Library Python modules in the Lib/ directory

   3.14bugs and security fixesbugs and security fixes

   on Mar 12, 2025
5. github-project-automation

   added this to asyncioon Mar 12, 2025
6. github-project-automation

   moved this to Todo in asyncioon Mar 12, 2025
7. hroncok commented on Mar 12, 2025

   

   hroncok

   on Mar 12, 2025

   ContributorAuthor

   More actions

   As a workaround, from asyncio.events import _BaseDefaultEventLoopPolicy currently works, indeed.

   I realize this was probably never meant to be a public API. It just kinda was.
8. kumaraditya303 commented on Mar 12, 2025

   

   kumaraditya303

   on Mar 12, 2025

   Contributor

   More actions

   BaseDefaultEventLoopPolicy is an undocumented and private class of a private submodule of asyncio. Only the stuff exposed from toplevel asyncio and that is documented is considered public.

   uvloop should change its code to not use private class and instead use abstract policy class.
9. picnixz commented on Mar 12, 2025

   

   picnixz

   on Mar 12, 2025

   Member

   More actions

   I realize this was probably never meant to bea public API. It just kinda was.

   Yes, it's something we had a lot in Sphinx where we named private objects with public names and didn't document them / export them, making them implicitly private, but not everyone assumes this kind of convention, which then makes refactoring usually breaking.

   As for whether the lack of a changelog entry, it has been added afterwards (#128269 and #128290)
10. kumaraditya303 commented on Mar 28, 2025

    

    kumaraditya303

    on Mar 28, 2025

    Contributor

    More actions

    Closing as it is wont-fix
11. kumaraditya303

    closed this as not plannedon Mar 28, 2025
12. github-project-automation

    moved this from Todo to Done in asyncioon Mar 28, 2025
13. musicinmybrain

    added 2 commits that reference this issue on Jun 27, 2025

    Fix test_loop_auto for Python 3.14

    6a02026

    Fix test_loop_auto for Python 3.14

    d522a10
14. fantix

    added 2 commits that reference this issue on Sep 14, 2025

    Workaround missing BaseDefaultEventLoopPolicy in Python 3.14

    74e109e

    CPython 3.14-3.16 compat

    20241b0

Issue actions