René's URL Explorer Experiment

{"@context":"https://schema.org","@type":"DiscussionForumPosting","headline":"Calling `ShareableList.count` in threads aborts: `Assertion 'self-\u003eexports == 0' failed`","articleBody":"# Crash report\n\n### What happened?\n\nIt's possible to abort the interpreter by calling `multiprocessing.shared_memory.ShareableList.count` in threads with `PYTHON_GIL=0` in a debug build:\n\n```python\nimport gc\nimport multiprocessing.shared_memory\nfrom threading import Thread\n\nobj = multiprocessing.shared_memory.ShareableList(\"Uq..SeDAmB+EBrkLl.SG.Z+Z.ZdsV..wT+zLxKwdN\\b\")\n\nfor x in range(10):\n    Thread(target=obj.count, args=(1,)).start()\n\ndel obj\ngc.collect()\n```\n\nResult:\n```python\nException ignored in: \u003cfunction SharedMemory.__del__ at 0x200006bbfb0\u003e\nTraceback (most recent call last):\n  File \"/home/danzin/projects/mycpython/Lib/multiprocessing/shared_memory.py\", line 189, in __del__\n    self.close()\n  File \"/home/danzin/projects/mycpython/Lib/multiprocessing/shared_memory.py\", line 229, in close\n    self._buf.release()\nBufferError: memoryview has 2 exported buffers\npython: Objects/memoryobject.c:1143: memory_dealloc: Assertion `self-\u003eexports == 0' failed.\nAborted\n```\nFound using [fusil](https://github.com/devdanzin/fusil) by @vstinner.\n\n### CPython versions tested on:\n\nCPython main branch\n\n### Operating systems tested on:\n\nLinux\n\n### Output from running 'python -VV' on the command line:\n\nPython 3.14.0a2+ experimental free-threading build (heads/main-dirty:c9b399fbdb0, Nov 19 2024, 20:12:48) [GCC 11.4.0]\n\n\u003c!-- gh-linked-prs --\u003e\n### Linked PRs\n* gh-127412\n* gh-128019\n\u003c!-- /gh-linked-prs --\u003e\n","author":{"url":"https://github.com/devdanzin","@type":"Person","name":"devdanzin"},"datePublished":"2024-11-21T02:00:57.000Z","interactionStatistic":{"@type":"InteractionCounter","interactionType":"https://schema.org/CommentAction","userInteractionCount":4},"url":"https://github.com/127085/cpython/issues/127085"}