[3.13] gh-127582: Make object resurrection thread-safe for free threading. (GH-127612) #127659
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… threading. (pythonGH-127612) Objects may be temporarily "resurrected" in destructors when calling finalizers or watcher callbacks. We previously undid the resurrection by decrementing the reference count using `Py_SET_REFCNT`. This was not thread-safe because other threads might be accessing the object (modifying its reference count) if it was exposed by the finalizer, watcher callback, or temporarily accessed by a racy dictionary or list access. This adds internal-only thread-safe functions for temporary object resurrection during destructors. (cherry picked from commit f4f5308) Co-authored-by: Sam Gross <[email protected]>
This was referenced Dec 5, 2024
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Objects may be temporarily "resurrected" in destructors when calling finalizers or watcher callbacks. We previously undid the resurrection by decrementing the reference count using
Py_SET_REFCNT. This was not thread-safe because other threads might be accessing the object (modifying its reference count) if it was exposed by the finalizer, watcher callback, or temporarily accessed by a racy dictionary or list access.This adds internal-only thread-safe functions for temporary object resurrection during destructors.
(cherry picked from commit f4f5308)
Py_SET_REFCNTin destructors #127582