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{"@context":"https://schema.org","@type":"DiscussionForumPosting","headline":"concurrent.interpreters.NotShareableError: object could not be unpickled","articleBody":"# Bug report\n\n### Bug description:\n\nContext:\n1. https://github.com/python/cpython/issues/142414#issuecomment-3639360631\n2. https://github.com/python/cpython/pull/142515 should fix the issue found in https://github.com/python/cpython/issues/142414.\n\nAnd during the time I was exploring the singleton removal, I found out it's possible, but the test may miss an edge case:\n\n```python\nfrom concurrent import interpreters                                                                                                             \nfrom concurrent.interpreters import _queues as queues\nimport unittest\n\nclass Tests(unittest.TestCase):\n    def test_cross_interpreter_unbound_identity(self):\n        # Prepare shared queues.\n        input_q = interpreters.create_queue()\n        input_q.put(queues.UNBOUND)\n        result_q = interpreters.create_queue()\n\n        # Create a sub-interpreter.\n        interp = interpreters.create()\n        interp.prepare_main({\"input_q\": input_q, \"result_q\": result_q})\n\n        # Run and compare the items in queue.\n        interp.exec(\"\"\"\nfrom concurrent.interpreters import _queues as queues\nobj = input_q.get()\nis_identical = (obj is queues.UNBOUND)\nresult_q.put(is_identical)\n\"\"\")\n        is_identical = result_q.get()\n        self.assertTrue(is_identical, \"UNBOUND identity mismatch across interpreters\")\n\nif __name__ == \"__main__\":\n    unittest.main()\n```\n\nThis test is failed without making the object picklable:\n\n```\nERROR: test_cross_interpreter_unbound_identity (__main__.Tests.test_cross_interpreter_unbound_identity)\n----------------------------------------------------------------------\nTraceback (most recent call last):\n  File \"/usr/local/google/home/kirchou/lamdef/cpython/Lib/test/test_addd.py\", line 17, in test_cross_interpreter_unbound_identity\n            interp.exec(\"\"\"\n            ~~~~~~~~~~~^^^^\n    from concurrent.interpreters import _queues as queues\n    ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^\n    ...\u003c2 lines\u003e...\n    result_q.put(is_identical)\n    ^^^^^^^^^^^^^^^^^^^^^^^^^^\n    \"\"\")\n    ^^^^\n  File \"/usr/local/google/home/kirchou/lamdef/cpython/Lib/concurrent/interpreters/__init__.py\", line 217, in exec\n    raise ExecutionFailed(excinfo)\nconcurrent.interpreters.ExecutionFailed: concurrent.interpreters.NotShareableError: object could not be unpickled\n\nUncaught in the interpreter:\n\nTraceback (most recent call last):\n  File \"/usr/local/google/home/kirchou/lamdef/cpython/Lib/concurrent/interpreters/_crossinterp.py\", line 65, in __new__\n    raise Exception(f'use {cls._MODULE}.{cls._NAME}')\nException: use concurrent.interpreters._crossinterp.UNBOUND\n\nThe above exception was the direct cause of the following exception:\n\nTraceback (most recent call last):\n  File \"\u003cscript\u003e\", line 3, in \u003cmodule\u003e\n  File \"/usr/local/google/home/kirchou/lamdef/cpython/Lib/concurrent/interpreters/_queues.py\", line 261, in get\n    obj, unboundop = _queues.get(self._id)\n                     ~~~~~~~~~~~^^^^^^^^^^\nconcurrent.interpreters.NotShareableError: object could not be unpickled\n```\n\n### CPython versions tested on:\n\nCPython main branch\n\n### Operating systems tested on:\n\nLinux","author":{"url":"https://github.com/note35","@type":"Person","name":"note35"},"datePublished":"2025-12-11T14:13:53.000Z","interactionStatistic":{"@type":"InteractionCounter","interactionType":"https://schema.org/CommentAction","userInteractionCount":3},"url":"https://github.com/142572/cpython/issues/142572"}