Performance regression with cyclic GC vs 3.13
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- Python
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Description
Bug report
Bug description:
While working on the free-threaded GC, I noticed this performance regression with the default build GC. Running the attached script (bm_gc_collect.py) with the main branch of Python shows much worse performance vs 3.13. I get 20.8 seconds for the main branch and 3.3 seconds for 3.13. Adding gc.disable() before calling benchmark_collection() seems to fix it.
CPython versions tested on:
CPython main branch
Operating systems tested on:
Linux
Linked PRs
- gh-132488
Contributor guide
First steps
- Read the whole issue, then the project's contributing guide.
- Comment on the issue to say you are picking it up — it saves two people doing the same work.
- Fork the repository and make your change on a branch.
- Open a pull request that references the issue number.
Research direction
Start by running the attached bm_gc_collect.py script on CPython main and Python 3.13 under Linux, comparing the reported collection times with and without gc.disable(). Read the linked PR gh-132488 and the free-threaded GC changes it addresses; done means resolving the regression so the benchmark is no longer substantially slower than 3.13.
Written by the indexing model from the issue text.
Assessment
- Tech stack
- python
- Domain
- performance
- Issue type
- Bug
- Difficulty
- 4/5
- Estimated time
- 3-5 days
- Activity status
- Stale
- Clarity
- Mostly clear
- Newbie friendliness
- 25/100