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GeezerVison is showing github.com — gh-159739: Avoid quadratic grouped-address parsing by jelle-openai · Pull Request #159990 · python/cpython

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@jelle-openai

@jelle-openai jelle-openai commented Oct 20, 2026 •
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Avoid quadratic grouped-address parsing. email.utils.getaddresses() parses a group by repeatedly concatenating the accumulated address list with each newly parsed member. Each concatenation copies all prior entries, so a group with many members takes quadratic time and can consume excessive CPU. Extending the list in place avoids that repeated copying.

Backport to 3.15 and 3.14.

  • Issue: Fix minor safety issues #159739

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@jelle-openai
pythongh-159739: Avoid quadratic grouped-address parsing
4e8385f 
Backport to 3.15 and 3.14.
@jelle-openai
jelle-openai requested a review from a team as a code owner October 20, 2026 23:23
@bedevere-app bedevere-app Bot mentioned this pull request Oct 20, 2026
Fix minor safety issues #159739
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@bedevere-app bedevere-app Bot added the awaiting review label Oct 20, 2026
@JelleZijlstra

JelleZijlstra commented Oct 20, 2026

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Not going to backport this as it's a performance improvement.
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@JelleZijlstra
JelleZijlstra enabled auto-merge (squash) October 21, 2026 18:46
@JelleZijlstra
JelleZijlstra merged commit 080fc54 into python:main Oct 21, 2026
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@bedevere-app bedevere-app Bot removed the awaiting review label Oct 21, 2026
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@jelle-openai @JelleZijlstra
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