[3.13] gh-87135: Hang non-main threads that attempt to acquire the GIL during finalization (GH-105805)#137827
Merged
gpshead merged 4 commits intopython:3.13from Aug 17, 2025
Merged
Conversation
…the GIL during finalization (pythonGH-105805) Instead of surprise crashes and memory corruption, we now hang threads that attempt to re-enter the Python interpreter after Python runtime finalization has started. These are typically daemon threads (our long standing mis-feature) but could also be threads spawned by extension modules that then try to call into Python. This marks the `PyThread_exit_thread` public C API as deprecated as there is no plausible safe way to accomplish that on any supported platform in the face of things like C++ code with finalizers anywhere on a thread's stack. Doing this was the least bad option. (cherry picked from commit 8cc5aa4) Co-authored-by: Jeremy Maitin-Shepard <[email protected]> Co-authored-by: Gregory P. Smith <[email protected]>
This was referenced Aug 15, 2025
gpshead
force-pushed
the
backport-8cc5aa4-3.13
branch
from
4f77306 to
977b0d4
Compare
gpshead
added
type-bug
gpshead
force-pushed
the
backport-8cc5aa4-3.13
branch
from
977b0d4 to
f412737
Compare
gpshead
added
the
🔨 test-with-buildbots
bedevere-bot
removed
the
🔨 test-with-buildbots
serhiy-storchaka
approved these changes
Aug 15, 2025
Member
serhiy-storchaka
left a comment
serhiy-storchaka
left a comment
There was a problem hiding this comment.
I cannot say it LGTM, but it looks less bad than anything else.
Member
Author
|
I'll leave this PR around for reference, but do not intend to merge it so late in the 3.13 release cycle even though I believe this least bad option is the only viable one. It is a behavior change, even if the existing behavior is an undertiministic sometimes crashing or sometimes working. See #87135 (comment) and #123940 (comment) for rationale from @encukou about invasiveness of such a change as in a bugfix release. |
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
Sign up for free
to join this conversation on GitHub.
Already have an account?
Sign in to comment
4 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.
Instead of surprise crashes and memory corruption, we now hang threads that attempt to re-enter the Python interpreter after Python runtime finalization has started. These are typically daemon threads (our long standing mis-feature) but could also be threads spawned by extension modules that then try to call into Python. This backport documents that the
PyThread_exit_threadpublic C API should not be used (deprecated in 3.14) as there is no plausible safe way to accomplish that on any supported platform in the face of things like C++ code with finalizers anywhere on a thread's stack. Doing this was the least bad option.(cherry picked from commit 8cc5aa4)
📚 Documentation preview 📚: https://cpython-previews--137827.org.readthedocs.build/