mirrors/cpython
1
0
Fork 0
mirror of https://github.com/python/cpython.git synced 2025-09-26 18:29:57 +00:00
Code Issues Projects Releases Packages Wiki Activity Actions 10

Issue #16602: When a weakref's target was part of a long deallocation chain, the object could remain reachable through its weakref even though its refcount had dropped to zero.

Browse source 
Thanks to Eugene Toder for diagnosing and reporting the issue.
This commit is contained in:
Antoine Pitrou 2012-12-08 21:15:26 +01:00
parent bd5279ea24
commit d38c990bb7
5 changed files with 39 additions and 4 deletions
Download patch file Download diff file Expand all files Collapse all files

12
Include/weakrefobject.h
View file

@ -66,7 +66,17 @@ PyAPI_FUNC(Py_ssize_t) _PyWeakref_GetWeakrefCount(PyWeakReference *head);
PyAPI_FUNC(void) _PyWeakref_ClearRef(PyWeakReference *self);
#define PyWeakref_GET_OBJECT(ref) (((PyWeakReference *)(ref))->wr_object)
/* Explanation for the Py_REFCNT() check: when a weakref's target is part
of a long chain of deallocations which triggers the trashcan mechanism,
clearing the weakrefs can be delayed long after the target's refcount
has dropped to zero. In the meantime, code accessing the weakref will
be able to "see" the target object even though it is supposed to be
unreachable. See issue #16602. */
#define PyWeakref_GET_OBJECT(ref) \
(Py_REFCNT(((PyWeakReference *)(ref))->wr_object) > 0 \
? ((PyWeakReference *)(ref))->wr_object \
: Py_None)
#ifdef __cplusplus