gh-127521: Mark list as "shared" before resizing if necessary #127524
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In the free threading build, f a non-owning thread resizes a list, it must use QSBR to free the old list array because there may be a concurrent access (without a lock) from the owning thread. To match the pattern in dictobject.c, we just mark the list as "shared" before resizing if it's from a non-owning thread and not already marked as shared.
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The repro from @vstinner no longer crashes: I think there's probably cleaner ways of structuring this, but I figured we might as well match the pattern in dictobject.c for now. We can refactor it a bit later. |
mpage
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Dec 2, 2024
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Thanks @colesbury for the PR 🌮🎉.. I'm working now to backport this PR to: 3.13. |
miss-islington
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Dec 2, 2024
…ythonGH-127524) In the free threading build, if a non-owning thread resizes a list, it must use QSBR to free the old list array because there may be a concurrent access (without a lock) from the owning thread. To match the pattern in dictobject.c, we just mark the list as "shared" before resizing if it's from a non-owning thread and not already marked as shared. (cherry picked from commit c7dec02) Co-authored-by: Sam Gross <colesbury@gmail.com>
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GH-127533 is a backport of this pull request to the 3.13 branch. |
colesbury
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Dec 3, 2024
…H-127524) (GH-127533) In the free threading build, if a non-owning thread resizes a list, it must use QSBR to free the old list array because there may be a concurrent access (without a lock) from the owning thread. To match the pattern in dictobject.c, we just mark the list as "shared" before resizing if it's from a non-owning thread and not already marked as shared. (cherry picked from commit c7dec02) Co-authored-by: Sam Gross <colesbury@gmail.com>
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Thanks for the quick fix @colesbury and @mpage! |
colesbury
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Dec 3, 2024
We were missing locks around some list operations in the free threading build.
colesbury
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Dec 3, 2024
We were missing locks around some list operations in the free threading build.
colesbury
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Dec 3, 2024
We were missing locks around some list operations in the free threading build.
srinivasreddy
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Jan 8, 2025
…ython#127524) In the free threading build, if a non-owning thread resizes a list, it must use QSBR to free the old list array because there may be a concurrent access (without a lock) from the owning thread. To match the pattern in dictobject.c, we just mark the list as "shared" before resizing if it's from a non-owning thread and not already marked as shared.
ebonnal
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Jan 12, 2025
…ython#127524) In the free threading build, if a non-owning thread resizes a list, it must use QSBR to free the old list array because there may be a concurrent access (without a lock) from the owning thread. To match the pattern in dictobject.c, we just mark the list as "shared" before resizing if it's from a non-owning thread and not already marked as shared.
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In the free threading build, if a non-owning thread resizes a list, it must use QSBR to free the old list array because there may be a concurrent access (without a lock) from the owning thread.
To match the pattern in dictobject.c, we just mark the list as "shared" before resizing if it's from a non-owning thread and not already marked as shared.