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{"@context":"https://schema.org","@type":"DiscussionForumPosting","headline":"Memory leak when throwing exceptions in .NET and catching in Python","articleBody":"### Environment\r\n\r\n-   Pythonnet version: 2.5.2\r\n-   Python version: issue verified on 3.7.2, 3.7.7 and 3.8.6\r\n-   Operating System: Windows 10 64bit\r\n-   .NET Runtime: .NET Framework 4.7.2\r\n\r\n### Details\r\n\r\nHello everybody and thanks for this great piece of Software!\r\n\r\nThe basic issue is:\r\n* if I throw a .NET exception from within C# code\r\n* and the exception moves into the python space\r\n  * i.e. the C# method was called from python\r\n* then the memory of the exception does not get released anymore\r\n\r\nThis becomes apparent when you throw quite a lot of exceptions and your applications runs 24/7.\r\n\r\n#### Reproducability\r\n\r\nThe issue is fairly easy to reproduce. I have also setup a sample repository, which reproduces the issue.\r\n\r\nhttps://github.com/Rookfighter/pythonnet-memleak-exceptions\r\n\r\nThe basis instruction are:\r\n\r\n* setup a Visual Studio Project of the type \"Class Library .NET Framework 4.7.2\"\r\n* create a `ExceptionThrower` class\r\n\r\n```cs\r\nusing System;\r\n\r\nnamespace LeakingExceptions\r\n{\r\n    public class ExceptionThrower\r\n    {\r\n        public void ThrowException()\r\n        {\r\n            throw new Exception(\"a simple exception\");\r\n        }\r\n    }\r\n}\r\n```\r\n\r\n* create a python script which imports the assembly\r\n* create a `ExceptionThrower` object and call `ThrowException` within a looped `try except` block\r\n\r\n```python\r\nimport os\r\nimport __main__\r\n\r\nimport clr\r\n\r\n# bin dir must be adjusted to your relative path!\r\nbin_dir = os.path.abspath(os.path.join(os.path.dirname(__main__.__file__), '../Source/LeakingExceptions/bin/Debug'))\r\nclr.AddReference(os.path.join(bin_dir, 'LeakingExceptions'))\r\n\r\nfrom LeakingExceptions import ExceptionThrower\r\n\r\nthrower = ExceptionThrower()\r\n\r\nwhile True:\r\n    try:\r\n        thrower.ThrowException()\r\n    except:\r\n        pass\r\n```\r\n\r\n* in the task manager you can then watch the application to accumulate memory and never release it\r\n\r\n![memleak_taskmgr](https://user-images.githubusercontent.com/2543949/123053735-7dc5ba00-d404-11eb-95a2-9d9fc8ea1c63.png)\r\n\r\n\r\n","author":{"url":"https://github.com/Rookfighter","@type":"Person","name":"Rookfighter"},"datePublished":"2021-06-23T07:23:42.000Z","interactionStatistic":{"@type":"InteractionCounter","interactionType":"https://schema.org/CommentAction","userInteractionCount":0},"url":"https://github.com/1476/pythonnet/issues/1476"}