gh-140795: fetch thread state once on fast path for critical sections #141406
+65
−37
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
colesbury
reviewed
Nov 13, 2025
Contributor
|
How much of a difference does this make to |
Contributor
Author
It is ~5% faster on macOS with this change. |
colesbury
approved these changes
Nov 21, 2025
StanFromIreland
pushed a commit
to StanFromIreland/cpython
that referenced
this pull request
Dec 6, 2025
ashm-dev
pushed a commit
to ashm-dev/cpython
that referenced
this pull request
Dec 8, 2025
Sign up for free
to join this conversation on GitHub.
Already have an account?
Sign in to comment
2 participants
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Outdated suggestions cannot be applied.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.
Currently on the fastpath for critical section where the objects are not locked, the thread state is fetched twice once while acquiring it and once while releasing it. This PR optimizes it to fetch it once and store it (in a temp variable on stack) so that on the fastpath thread state is fetched once.
This should help performance in shared modules such as
sslwhere thread state access is slower because of extra function call to_PyThreadState_GetCurrent.