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Forward-port generational GC #148726
Description
Feature or enhancement
Proposal:
It was decided to revert the incremental GC and restore the generational GC from Python 3.13.
After discussing with @nascheme, we plan to forward-port the generational GC from 3.13 with minimal changes.
Here is the plan:
3.14
- Forward-port the generational GC from 3.13 with minimal changes
- Backport the heap_size calculation logic
3.15
- Forward port from 3.14
- Backport weakref's callbacks changes (b6b99bf, 350c58b, 654b8d9)
- Backport changes required for pystats (c98c5b3)
- Backport GC frame for Tachyon (336366f)
- Backport extended data for callbacks: duration, candidates (598d4c6, 227b9d3)
- Backport gc-stats from external processes (Add a module for monitoring GC statistics #146527)
AFAICT, these are all the changes that need to be forward-ported or backported for the 3.14 and 3.15.
Has this already been discussed elsewhere?
I have already discussed this feature proposal on Discourse
Links to previous discussion of this feature:
https://discuss.python.org/t/reverting-the-incremental-gc-in-python-3-14-and-3-15/107014
Linked PRs
- [3.14] GH-148726: Forward-port generational GC #148720
- GH-148726: Forward-port generational GC. #148746
- [3.14] GH-148726: Forward-port generational GC (another way) #148772
- [3.14] GH-148726: Add heap_size to _gc_runtime_state #149025
- GH-148726: Add heap_size to generational GC #149195
- gh-148726: Document the GC change in What's New in Python 3.14 #149209
- [3.14] gh-148726: Document the GC change in What's New in Python 3.14 (GH-149209) #149249
- gh-148726: Add gc changes to What's New #149398
Activity
[3.14] GH-148726: Forward-port generational GC (#148720)
sergey-miryanov commented on Apr 26, 2026
With #148720 landed, I'll open a PR for the heap_size backport.
[3.14] GH-148726: Add heap_size to _gc_runtime_state (#149025)
sergey-miryanov commented on Apr 29, 2026
#149025 has merged. I plan to forward-port the changes to the 3.15 branch once #148746 is merged.
GH-148726: Forward-port generational GC. (GH-148746)
gh-148726: Document the GC change in What's New in Python 3.14 (#149209)
[3.14] gh-148726: Document the GC change in What's New in Python 3.14 (…
GH-148726: Add heap_size to generational GC (#149195)
sergey-miryanov commented on May 5, 2026
All planned tasks done. Closing this out.
hugovk commented on May 5, 2026
Thank you for all your work on this!
hauntsaninja commented on May 5, 2026
Might be worth documenting in 3.15 What's New as well?
hugovk commented on May 5, 2026
Yes, I created #149398.
gh-148726: Add gc changes to What's New (#149398)
build(deps): update uv to v0.11.11
feat(github-release): update release uv ( 0.10.9 → 0.11.17 ) (#34)
feat(github-release): update release uv ( 0.10.9 → 0.11.19 ) (#43)