`list.sort` enhancement proposal: Adaptivity for `binarysort`
Open
@tim-one is already working on this.
Since Sep 16, 2025.
interpreter-core
performance
type-feature
- Dominant language
- Python
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Description
Feature or enhancement
Proposal:
Adding adaptivity to binarysort routine of list.sort.
See PR for specifics.
Initial Post (Outdated)
Note:
- This is POC that this has a observable impact.
- This is subject to further calibration and optimizations, but high level concept is dicusable.
- Will issue PR shortly.
Rationale
Galloping provides adaptivity when merging runs.
However, underlying binarysort always does O(nlogn).
Concept
The concept is simple:
binarysortoptionally does adaptive routine.- It has a mechanism to switch it off during the run and go to simple binarysort
- It returns 1 if it has completed full data with binary routine and 0 otherwise
timsortcallsbinarysort- If it returns 1, then use it again next time
- If it returns 0, then use
binarysortwithout adaptivity next time - increase number of simple
binarysortruns before next attempt of adaptive run with every 0 returned
High level results
A0is currentA1is with adaptivityPmeans performance / runtimeCmeans comparison count- Aggregate numbers for all datasets combined are in the title
- Plain integers and floats
- Integers and floats wrapped in
list, so comparisons are__lt__calls, thus more expensive
So the benefit is higher when comparisons cost more.
But there is some benefit for optimized comparisons as well.
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/sorting-adaptivity-improvement/103700
Linked PRs
- gh-138947
- gh-139342
- gh-139969
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