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{"@context":"https://schema.org","@type":"DiscussionForumPosting","headline":"Releasing GIL in long-running C# method causes  \"Fatal Python error: PyEval_SaveThread: the function must be called with the GIL held, but the GIL is released (the current Python thread state is NULL)\"","articleBody":"### Environment\r\n\r\n-   Pythonnet version: 3.0.1\r\n-   Python version: 3.9.13\r\n-   Operating System: Windows 11\r\n-   .NET Runtime: .NET Core 3.1\r\n\r\n### Details\r\n\r\nI'm trying to prevent a long running method in C# from blocking execution in Python. I followed the guidance on https://github.com/pythonnet/pythonnet/wiki/Threading but I am getting a crash.\r\n\r\n-   What commands did you run to trigger this issue? If you can provide a\r\n    [Minimal, Complete, and Verifiable example](http://stackoverflow.com/help/mcve)\r\n    this will help us understand the issue.\r\n\r\n```python\r\nimport pythonnet\r\npythonnet.load('coreclr')\r\n\r\nimport os\r\nbin_path = os.path.normpath(os.path.dirname(os.path.abspath(__file__)) + \"/../LongRunningTask/bin/Debug/netcoreapp3.1\")\r\n\r\nimport clr\r\nclr.AddReference(os.path.join(bin_path, \"LongRunningTask\"))\r\nclr.AddReference(\"System\")\r\n\r\nfrom LongRunningTask import LongRunningTask\r\nfrom threading import Thread, Timer\r\n\r\nt1 = Thread(target=LongRunningTask.Run)\r\n\r\nt1.daemon = True\r\nt1.start()\r\n```\r\n\r\n```csharp\r\nusing System.Threading;\r\nusing Python.Runtime;\r\n\r\nnamespace LongRunningTask\r\n{\r\n    public class LongRunningTask\r\n    {\r\n        public static void Run()\r\n        {\r\n            var state = PythonEngine.BeginAllowThreads();\r\n            Thread.Sleep(1000);\r\n            PythonEngine.EndAllowThreads(state);\r\n        }\r\n    }\r\n}\r\n```\r\n\r\n-   If there was a crash, please include the traceback here.\r\n\r\n```\r\nFatal Python error: PyGILState_Release: thread state 000001D4A5CA2A40 must be current when releasing\r\nPython runtime state: initialized\r\n\r\nThread 0x00001c08 (most recent call first):\r\n  File \"C:\\Program Files (x86)\\Microsoft Visual Studio\\Shared\\Python39_64\\lib\\threading.py\", line 917 in run\r\n  File \"C:\\Program Files (x86)\\Microsoft Visual Studio\\Shared\\Python39_64\\lib\\threading.py\", line 980 in _bootstrap_inner\r\n  File \"C:\\Program Files (x86)\\Microsoft Visual Studio\\Shared\\Python39_64\\lib\\threading.py\", line 937 in _bootstrap\r\n\r\nCurrent thread 0x00005f6c (most recent call first):\r\n  File \"C:\\Users\\shersh\\AppData\\Roaming\\Python\\Python39\\site-packages\\clr_loader\\types.py\", line 64 in __call__\r\n  File \"C:\\Users\\shersh\\AppData\\Roaming\\Python\\Python39\\site-packages\\pythonnet\\__init__.py\", line 157 in unload\r\nFatal error. System.AccessViolationException: Attempted to read or write protected memory. This is often an indication that other memory is corrupt.\r\n   at Python.Runtime.Runtime.PyGILState_Release(Python.Runtime.Native.PyGILState)\r\n   at Python.Runtime.PythonEngine.ReleaseLock(Python.Runtime.Native.PyGILState)\r\n   at Python.Runtime.Py+GILState.Dispose()\r\n   at Python.Runtime.Loader.Shutdown(IntPtr, Int32)\r\n```\r\n","author":{"url":"https://github.com/sherryyshi","@type":"Person","name":"sherryyshi"},"datePublished":"2023-08-04T21:41:31.000Z","interactionStatistic":{"@type":"InteractionCounter","interactionType":"https://schema.org/CommentAction","userInteractionCount":1},"url":"https://github.com/2208/pythonnet/issues/2208"}