René's URL Explorer Experiment

{"@context":"https://schema.org","@type":"DiscussionForumPosting","headline":"[Bug]: High memory usage in `Figure.savefig`","articleBody":"### Bug summary\r\n\r\nWhen saving figures with large data images (`imshow`), matplotlib version 3.10.0 uses ~4.2 times the amount of memory, and runs ~2.5 times slower.\r\n\r\n### Code for reproduction\r\n\r\n```Python\r\n#!/usr/bin/env -S uv run --with humanize --with numpy --with \"matplotlib==3.10\"\r\n\r\nimport tracemalloc\r\n\r\nimport humanize\r\nimport matplotlib.pyplot as plt\r\nimport numpy as np\r\n\r\ntracemalloc.start()\r\n\r\nfig, ax = plt.subplots()\r\nax.imshow(np.zeros((10_000, 10_000)))\r\n\r\nfig.savefig(\"test.png\")\r\n\r\n_, peak = tracemalloc.get_traced_memory()\r\n\r\nprint(f\"Memory usage peaked at {humanize.naturalsize(peak)}\")\r\n```\r\n\r\n\r\n### Actual outcome\r\n\r\n```\r\nMemory usage peaked at 7.2 GB\r\n```\r\n\r\n### Expected outcome\r\n\r\n```\r\nMemory usage peaked at 1.7 GB\r\n```\r\n\r\nThis is the result when the shebang in the code example is changed to \"matplotlib\u003c3.10\", or when the `fig.savefig(\"test.png\")` line is removed.\r\n\r\n### Additional information\r\n\r\nMay be related to #28904, although switching the backend to Cairo doesn't affect the results.\r\n\r\n### Operating system\r\n\r\nArch\r\n\r\n### Matplotlib Version\r\n\r\n3.10.0\r\n\r\n### Matplotlib Backend\r\n\r\nagg\r\n\r\n### Python version\r\n\r\nPython 3.13.0\r\n\r\n### Jupyter version\r\n\r\n_No response_\r\n\r\n### Installation\r\n\r\nNone","author":{"url":"https://github.com/zqianem","@type":"Person","name":"zqianem"},"datePublished":"2025-01-08T21:18:05.000Z","interactionStatistic":{"@type":"InteractionCounter","interactionType":"https://schema.org/CommentAction","userInteractionCount":4},"url":"https://github.com/29434/matplotlib/issues/29434"}