PyCell_GET/SET are not thread-safe in free-threaded builds #127271
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nascheme
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Nov 26, 2024
These macros are not safe to use in the free-threaded build. Use `PyCell_GetRef()` and `PyCell_SetTakeRef()` instead. Add `PyCell_GET` to the free-threading howto table of APIs that return borrowed refs. Add critical sections to `PyCell_GET` and `PyCell_SET`.
nascheme
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Dec 3, 2024
* Replace uses of `PyCell_GET` and `PyCell_SET`. These macros are not safe to use in the free-threaded build. Use `PyCell_GetRef()` and `PyCell_SetTakeRef()` instead. * Since `PyCell_GetRef()` returns a strong rather than borrowed ref, some code restructuring was required, e.g. `frame_get_var()` returns a strong ref now. * Add critical sections to `PyCell_GET` and `PyCell_SET`. * Move critical_section.h earlier in the Python.h file. * Add `PyCell_GET` to the free-threading howto table of APIs that return borrowed refs. * Add additional unit tests for free-threading.
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Bug report
Bug description:
The
PyCell_GETandPyCell_SETmacros are not safe for free-threading builds. First, they don't the correct locking. Second,PyCell_GETreturns a borrowed reference.For CPython internals, the usages of these macros can be replaced (either with
PyCell_GetRef(),PyCell_SetTakeRef(), or similar). For external API users, these macros will need to be marked as deprecated, at least for free-threaded builds.CPython versions tested on:
CPython main branch
Operating systems tested on:
No response
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