gh-137103: A faster check_circular #137286
Open
Conversation
This file contains hidden or bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
picnixz
reviewed
Aug 1, 2025
picnixz
reviewed
Aug 4, 2025
picnixz
reviewed
Aug 4, 2025
|
Ok, looks like everything's good for me. Could you add a NEWS entry? also you could add a What's New entry under "Optimizations". |
Sign up for free
to join this conversation on GitHub.
Already have an account?
Sign in to comment
Add this suggestion to a batch that can be applied as a single commit.
This suggestion is invalid because no changes were made to the code.
Suggestions cannot be applied while the pull request is closed.
Suggestions cannot be applied while viewing a subset of changes.
Only one suggestion per line can be applied in a batch.
Add this suggestion to a batch that can be applied as a single commit.
Applying suggestions on deleted lines is not supported.
You must change the existing code in this line in order to create a valid suggestion.
Outdated suggestions cannot be applied.
This suggestion has been applied or marked resolved.
Suggestions cannot be applied from pending reviews.
Suggestions cannot be applied on multi-line comments.
Suggestions cannot be applied while the pull request is queued to merge.
Suggestion cannot be applied right now. Please check back later.
Make
check_circularfaster without breaking API:It used to do
PyDict_Containscheck followed byPyDict_SetItemwhich means the hash is calculated two times and the hash lookup is done twice (which includes taking locks etc.) Instead do a speculativePyDict_SetItemand check if the dictionary size has increased. Checking the size is a simple memory read.The hash was still calculated two times for
PyDict_SetItemandPyDict_DelItem. Instead calculate it once and use the_KnownHashvariants for the functions to reuse the hash.