René's URL Explorer Experiment

{"@context":"https://schema.org","@type":"DiscussionForumPosting","headline":"Race condition with Process.GetCurrentProcess().Handle in WindowsLoader.GetAllModules","articleBody":"### Environment\r\n\r\n-   Pythonnet version: 3.0.0-rc4\r\n-   Python version: 3.7.7\r\n-   Operating System: Windows 10 21H2\r\n-   .NET Runtime: 5.0.17\r\n\r\n### Details\r\n\r\n-   I think there might be a race condition in `Python.Runtime.Platform.WindowsLoader.GetAllModules`. I am hitting this very sporadically when I initialize Python.NET from Python. The outer and inner exceptions are:\r\n```\r\nSystem.TypeInitializationException: The type initializer for 'Delegates' threw an exception.\r\n ---\u003e System.ComponentModel.Win32Exception (6): The handle is invalid.\r\n   at Python.Runtime.Platform.WindowsLoader.GetAllModules() in /tmp/build-via-sdist-sstjjspf/pythonnet-3.0.0rc4/src/runtime/Native/LibraryLoader.cs:line 153\r\n   at Python.Runtime.Platform.WindowsLoader.GetFunction(IntPtr hModule, String procedureName) in /tmp/build-via-sdist-sstjjspf/pythonnet-3.0.0rc4/src/runtime/Native/LibraryLoader.cs:line 133\r\n   at Python.Runtime.Runtime.Delegates.GetFunctionByName(String functionName, IntPtr libraryHandle) in /tmp/build-via-sdist-sstjjspf/pythonnet-3.0.0rc4/src/runtime/Runtime.Delegates.cs:line 296\r\n   at Python.Runtime.Runtime.Delegates..cctor() in /tmp/build-via-sdist-sstjjspf/pythonnet-3.0.0rc4/src/runtime/Runtime.Delegates.cs:line 110\r\n   --- End of inner exception stack trace ---\r\n   at Python.Runtime.Runtime.Delegates.get_PyGILState_Ensure() in /tmp/build-via-sdist-sstjjspf/pythonnet-3.0.0rc4/src/runtime/Runtime.Delegates.cs:line 319\r\n   at Python.Runtime.Runtime.PyGILState_Ensure() in /tmp/build-via-sdist-sstjjspf/pythonnet-3.0.0rc4/src/runtime/Runtime.cs:line 747\r\n   at Python.Runtime.PythonEngine.AcquireLock() in /tmp/build-via-sdist-sstjjspf/pythonnet-3.0.0rc4/src/runtime/PythonEngine.cs:line 472\r\n   at Python.Runtime.Py.GILState..ctor() in /tmp/build-via-sdist-sstjjspf/pythonnet-3.0.0rc4/src/runtime/Py.cs:line 27\r\n   at Python.Runtime.Py.GIL() in /tmp/build-via-sdist-sstjjspf/pythonnet-3.0.0rc4/src/runtime/Py.cs:line 13\r\n   at Python.Runtime.Loader.Initialize(IntPtr data, Int32 size) in /tmp/build-via-sdist-sstjjspf/pythonnet-3.0.0rc4/src/runtime/Loader.cs:line 26\r\n```\r\n\r\nLine numbers don't seem to line up exactly for me, but when I'm able to catch it in the debugger, it's the `throw new Win32Exception()` lines that trigger it.\r\n\r\nI think what might be happening in my case is that the handle `self` here: https://github.com/pythonnet/pythonnet/blob/v3.0.0-rc4/src/runtime/Native/LibraryLoader.cs#L140\r\nis being closed before one of the calls to `EnumProcessModules`.\r\n\r\nThe docs for `Process.GetCurrentProcess()` say that each invocation returns a new `Process` component; each instance opens its own handle to the current process, and that handle gets closed when `Process.Close` or `Process.Dispose` is called. Since a reference isn't being retained to the object returned by `Process.GetCurrentProcess()`, the garbage collector is able to collect it and its handle would be closed, which means that `self` is no longer valid.\r\n\r\nI think one solution would be something like...\r\n```\r\nusing (Process p = Process.GetCurrentProcess())\r\n{\r\n    EnumProcessModules(p.Handle, ...\r\n}\r\n```\r\n\r\nin order to keep the process alive while its handle is still being accessed. Thanks!","author":{"url":"https://github.com/sdao","@type":"Person","name":"sdao"},"datePublished":"2022-09-15T20:54:19.000Z","interactionStatistic":{"@type":"InteractionCounter","interactionType":"https://schema.org/CommentAction","userInteractionCount":0},"url":"https://github.com/1939/pythonnet/issues/1939"}