Issue 25935: OrderedDict prevents garbage collection if a circulary referenced class is used as key (original) (raw)

Issue25935

Created on 2015-12-23 23:39 by charettes, last changed 2022-04-11 14:58 by admin. This issue is now closed.

Messages (4)
msg256945 - (view)	Author: Simon Charette (charettes) *	Date: 2015-12-23 23:39
I attached a file with a reproduction test case that passes on Python 2.7 and 3.4 but fails on 3.5.0 and 3.5.1 This might be solved by the improvement planed in #25410.
msg257130 - (view)	Author: Serhiy Storchaka (serhiy.storchaka) *	Date: 2015-12-28 21:49
An OrderedDict owns two references to every key (as a dict and from a linked list). Therefore it should visit it twice in tp_traverse. Proposed patch fixes garbage collection for OrderedDict. It also rewrites OrderedDict clearing in more reentrant form (a linked list is detached from an OrderedDict before deallocating its nodes that can trigger executing user code).
msg258590 - (view)	Author: Roundup Robot (python-dev)	Date: 2016-01-19 12:49
New changeset 627575e9a7aa by Serhiy Storchaka in branch '3.5': Issue #25935: Garbage collector now breaks reference loops with OrderedDict. https://hg.python.org/cpython/rev/627575e9a7aa New changeset 5f0a08cfc4f6 by Serhiy Storchaka in branch 'default': Issue #25935: Garbage collector now breaks reference loops with OrderedDict. https://hg.python.org/cpython/rev/5f0a08cfc4f6
msg258592 - (view)	Author: Serhiy Storchaka (serhiy.storchaka) *	Date: 2016-01-19 13:50
In some cases (as in committed test) garbage collector was not able to collect a loop with OrderedDict at all.