René's URL Explorer Experiment

{"@context":"https://schema.org","@type":"DiscussionForumPosting","headline":"Tests that use \"image_comparison\" fail to cleanup on Windows ","articleBody":"\u003c!--To help us understand and resolve your issue, please fill out the form to the best of your ability.--\u003e\r\n\u003c!--You can feel free to delete the sections that do not apply.--\u003e\r\n\r\n### Bug report\r\n\r\nIt seems that unit tests that use the `image_comparison` decorator, specifically converting from SVG to PNG fail to cleanup after themselves in Windows 10.  \r\n\r\n**Actual outcome**\r\n\r\nSpecifically, the subprocess created to talk to inkscape doesn't close properly, and creates a ton of cascading Permission errors:\r\n\r\n```\r\n(mpldev) PS C:\\Users\\sjung\\MPLdev\\matplotlib\u003e pytest .\\lib\\matplotlib\\tests\\test_backend_svg.py::test_bold_font_output\r\n======================================================================= test session starts =======================================================================\r\nplatform win32 -- Python 3.8.3, pytest-6.2.2, py-1.10.0, pluggy-0.13.1\r\nrootdir: C:\\Users\\sjung\\Documents\\MyPrograms\\Python-programs\\Personal\\MPLdev\\matplotlib, configfile: pytest.ini\r\nplugins: cov-2.11.1, rerunfailures-9.1.1, timeout-1.4.2\r\ncollected 1 item\r\n\r\nlib\\matplotlib\\tests\\test_backend_svg.py .                                                                                                                   [100%]\r\n\r\n================================================================== 1 passed, 1 warning in 1.98s ===================================================================\r\nTraceback (most recent call last):\r\n  File \"c:\\users\\sjung\\miniconda3\\lib\\shutil.py\", line 617, in _rmtree_unsafe\r\n    os.rmdir(path)\r\nPermissionError: [WinError 32] The process cannot access the file because it is being used by another process: 'C:\\\\Users\\\\sjung\\\\AppData\\\\Local\\\\Temp\\\\tmpbqz_ngbr'\r\n\r\nDuring handling of the above exception, another exception occurred:\r\n\r\nTraceback (most recent call last):\r\n  File \"c:\\users\\sjung\\miniconda3\\lib\\tempfile.py\", line 803, in onerror\r\n    _os.unlink(path)\r\nPermissionError: [WinError 5] Access is denied: 'C:\\\\Users\\\\sjung\\\\AppData\\\\Local\\\\Temp\\\\tmpbqz_ngbr'\r\n\r\n\r\n[Above Error Repeats like 500 times, then we get]\r\n\r\n\r\nDuring handling of the above exception, another exception occurred:\r\n\r\nTraceback (most recent call last):\r\n  File \"c:\\users\\sjung\\miniconda3\\lib\\weakref.py\", line 642, in _exitfunc\r\n    f()\r\n  File \"c:\\users\\sjung\\miniconda3\\lib\\weakref.py\", line 566, in __call__\r\n    return info.func(*info.args, **(info.kwargs or {}))\r\n  File \"c:\\users\\sjung\\miniconda3\\lib\\tempfile.py\", line 818, in _cleanup\r\n    cls._rmtree(name)\r\n  File \"c:\\users\\sjung\\miniconda3\\lib\\tempfile.py\", line 814, in _rmtree\r\n    _shutil.rmtree(name, onerror=onerror)\r\n  File \"c:\\users\\sjung\\miniconda3\\lib\\shutil.py\", line 737, in rmtree\r\n    return _rmtree_unsafe(path, onerror)\r\n  File \"c:\\users\\sjung\\miniconda3\\lib\\shutil.py\", line 619, in _rmtree_unsafe\r\n    onerror(os.rmdir, path, sys.exc_info())\r\n  File \"c:\\users\\sjung\\miniconda3\\lib\\tempfile.py\", line 806, in onerror\r\n    cls._rmtree(path)\r\n\r\n[Repeated error]\r\n\r\n File \"c:\\users\\sjung\\miniconda3\\lib\\tempfile.py\", line 814, in _rmtree\r\n    _shutil.rmtree(name, onerror=onerror)\r\n  File \"c:\\users\\sjung\\miniconda3\\lib\\shutil.py\", line 737, in rmtree\r\n    return _rmtree_unsafe(path, onerror)\r\n  File \"c:\\users\\sjung\\miniconda3\\lib\\shutil.py\", line 594, in _rmtree_unsafe\r\n    entries = list(scandir_it)\r\nRecursionError: maximum recursion depth exceeded while calling a Python object\r\n\r\n```\r\n\r\nThe `_SVGConverter` subclasses `_Converter` (in lib/matplotlib/testing/compare.py) which should close the process atexit in it's `__del__` method:  \r\n\r\nhttps://github.com/matplotlib/matplotlib/blob/c81f58d375733bed70e921233f42f2b1d8dbfb57/lib/matplotlib/testing/compare.py#L107-L115\r\n\r\nAnd from my tests, this does get called properly but the error persists. Adding this exact same logic to the end of `_SVGConverter`'s `__call__` method seems to resolve the issue (although wastefull since a new process then gets created every time). \r\n\r\n**Expected outcome**\r\n\r\nI'd expect these test cases to cleanup after themselves and not leave empty temporary directories. \r\n\r\n**Matplotlib version**\r\n\u003c!--Please specify your platform and versions of the relevant libraries you are using:--\u003e\r\n  * Operating system: Windows 10\r\n  * Matplotlib version (`import matplotlib; print(matplotlib.__version__)`): 3.3.4.post2669+gce4c50de2.d20210328 (master as of today, installed from source)\r\n  * Matplotlib backend (`print(matplotlib.get_backend())`): TkAgg\r\n  * Python version: Happens with both Python 3.9.2 and 3.8.3\r\n  * Other libraries: Inkscape 1.0.2-2 (e86c870879, 2021-01-15)\r\n\r\n\u003c!--Please tell us how you installed matplotlib and python e.g., from source, pip, conda--\u003e\r\n\u003c!--If you installed from conda, please specify which channel you used if not the default--\u003e\r\n\r\n","author":{"url":"https://github.com/jungerm2","@type":"Person","name":"jungerm2"},"datePublished":"2021-03-28T20:53:34.000Z","interactionStatistic":{"@type":"InteractionCounter","interactionType":"https://schema.org/CommentAction","userInteractionCount":0},"url":"https://github.com/19809/matplotlib/issues/19809"}