René's URL Explorer Experiment

{"@context":"https://schema.org","@type":"DiscussionForumPosting","headline":"shelve: `Shelf.clear()` has very poor performance","articleBody":"# Bug report\r\n\r\nCalling the `clear` method on a `shelve.Shelf` object takes a very long time on databases that have thousands of entries.\r\n\r\nIt can be seen in this script, which creates a database with 10,000 entries and immediately clears it.\r\n\r\n```python\r\nimport os\r\nimport shelve\r\nimport tempfile\r\n\r\nwith tempfile.TemporaryDirectory() as tempdir:\r\n    filename = os.path.join(tempdir, \"test-shelf\")\r\n    with shelve.open(filename) as db:\r\n        items = {str(x):x for x in range(10000)}\r\n        db.update(items)\r\n        db.clear()\r\nprint(\"ok\")\r\n\r\n```\r\n\r\nOn my M2 Mac Mini, this script takes about 2.1 seconds.\r\n```\r\njames@iris ~ % time python shelve-clear-test.py\r\nok\r\npython shelve-clear-test.py  1.18s user 0.92s system 99% cpu 2.100 total\r\n```\r\n\r\nOn a Debian VPS:\r\n```\r\njames@asteroid:~$ time python3 shelve-clear-test.py \r\nok\r\n\r\nreal\t0m43.665s\r\nuser\t0m34.330s\r\nsys\t0m9.107s\r\n```\r\n\r\n# Your environment\r\n\r\n\u003c!-- Include as many relevant details as possible about the environment you experienced the bug in --\u003e\r\n\r\n- CPython versions tested on\r\n  - 3.11.2\r\n  - 3.11.4\r\n  - cpython/main branch\r\n- Operating system and architecture\r\n  - macOS/arm64 13.4.1\r\n  - Debian/x86_64 12.1\n\n\u003c!-- gh-linked-prs --\u003e\n### Linked PRs\n* gh-107090\n\u003c!-- /gh-linked-prs --\u003e\n","author":{"url":"https://github.com/jtcave","@type":"Person","name":"jtcave"},"datePublished":"2023-07-23T01:47:35.000Z","interactionStatistic":{"@type":"InteractionCounter","interactionType":"https://schema.org/CommentAction","userInteractionCount":2},"url":"https://github.com/107089/cpython/issues/107089"}