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gh-156341: Fix threading local fallback import - #157042

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Sohel2309:fix-156341-threading-local
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gh-156341: Fix threading local fallback import#157042
Sohel2309 wants to merge 3 commits into
python:mainfrom
Sohel2309:fix-156341-threading-local

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@Sohel2309

@Sohel2309 Sohel2309 commented Sep 6, 2026 •
edited by bedevere-app Bot
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Fixes #156341.

When _thread._local is unavailable, importing threading falls back to the pure Python _threading_local implementation. The fallback currently creates a circular initialization path that prevents threading from importing.

This change delays _thread_local_info initialization until after the main thread is registered and updates the fallback implementation to use the threading module explicitly.

Adds a regression test for the fallback import path.

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python-cla-bot Bot commented Sep 6, 2026 •
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@bedevere-app

bedevere-app Bot commented Sep 6, 2026

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Most changes to Python require a NEWS entry. Add one using the blurb_it web app or the blurb command-line tool.

If this change has little impact on Python users, wait for a maintainer to apply the skip news label instead.

@Sohel2309 Sohel2309 changed the title Fix threading local fallback import gh-156341: Fix threading local fallback import Sep 6, 2026
@bedevere-app bedevere-app Bot mentioned this pull request Sep 6, 2026
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BHUVANSH855
BHUVANSH855 reviewed Sep 7, 2026
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  • Rename Misc/NEWS.d/next/Core and Builtins/ to Misc/NEWS.d/next/Core_and_Builtins/.
  • Use literal markup in the NEWS entry: _threading_local and threading instead of single-backtick/default-role markup.

The Docs failure is caused by the unresolved Sphinx reference to _threading_local. Once fixed, please push the update and rerun CI.

@x42005e1f

x42005e1f commented Sep 9, 2026 •
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See #156357 (comment).

And why are you both updating the _threading_local module? What are you trying to achieve by doing that? You are already fixing the circular import in the threading module (for the main thread), and your "explicit use / lazy imports" do not solve the second problem I described (see #156341 (comment)). The change only adds overhead and nothing more.

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Broken circular import between threading and _threading_local

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@Sohel2309 @x42005e1f @BHUVANSH855