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{"@context":"https://schema.org","@type":"DiscussionForumPosting","headline":"Crash because of ownership assert in `PyObject_ClearManagedDict`","articleBody":"# Crash report\n\nRefs https://github.com/python/cpython/issues/151763\nOriginal description: https://gist.github.com/devdanzin/99b84915b197ae0ade7face262b8af66\n\nRepro: \n\n```python\nfrom unittest.mock import MagicMock\nfrom _testcapi import set_nomemory\n\nset_nomemory(200)              # fail allocations from the 200th onward (lands in shutdown GC)\n(MagicMock(), undefined_name)  # build a MagicMock (managed __dict__), then NameError abandons\n                               # it into a traceback cycle -\u003e survives to shutdown GC\n\n```\n\nI have a fix ready.\n\n\u003c!-- gh-linked-prs --\u003e\n### Linked PRs\n* gh-152255\n\u003c!-- /gh-linked-prs --\u003e\n","author":{"url":"https://github.com/sobolevn","@type":"Person","name":"sobolevn"},"datePublished":"2026-06-26T08:32:41.000Z","interactionStatistic":{"@type":"InteractionCounter","interactionType":"https://schema.org/CommentAction","userInteractionCount":0},"url":"https://github.com/152254/cpython/issues/152254"}