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[3.14] GH-139951: Fix major GC performance regression. Backport of GH-140262#140447

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markshannon merged 1 commit intopython:3.14fromfaster-cpython:backport-140262

Oct 23, 2025

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[3.14] GH-139951: Fix major GC performance regression. Backport of GH-140262#140447

markshannon merged 1 commit intopython:3.14fromfaster-cpython:backport-140262

Oct 23, 2025

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markshannon commentedOct 22, 2025•
edited by bedevere-appbot
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Count number of actually tracked objects, instead of trackable objects. This ensures that untracking tuples has the desired effect of reducing GC overhead
Do not track most untrackable tuples during creation. This prevents large numbers of small tuples causing execessive GCs.

Issue:Potentially serious regression in garbage collector performance in Python 3.14 #139951

Fix major GC performance regression

828e314

* Count number of actually tracked objects, instead of trackable objects. This ensures that untracking tuples has the desired effect of reducing GC overhead* Do not track most untrackable tuples during creation. This prevents large numbers of small tuples causing execessive GCs.