René's URL Explorer Experiment

{"@context":"https://schema.org","@type":"DiscussionForumPosting","headline":"Slow performances when running tests with `--experimental-test-coverage`","articleBody":"### Version\n\nv22.9.0\n\n### Platform\n\n```text\nDarwin N4V4PGFGPT 23.6.0 Darwin Kernel Version 23.6.0: Mon Jul 29 21:16:46 PDT 2024; root:xnu-10063.141.2~1/RELEASE_ARM64_T8112 arm64\n```\n\n\n### Subsystem\n\n_No response_\n\n### What steps will reproduce the bug?\n\nRun tests with `--experimental-test-coverage` option. Comparing it to other solutions (f.e. running Node tests and getting the coverage with `nyc`) this is way slower. For instance, on a repo with ~800 tests, collecting coverage with `nyc` takes 77s, while running with `--experimental-test-coverage` takes 148s.\n\n### How often does it reproduce? Is there a required condition?\n\nI can reproduce it every time I run the Node tests with the native test coverage option.\n\n### What is the expected behavior? Why is that the expected behavior?\n\nThe performances should be at least equal (ideally better) than with 3rd party dependencies (like `nyc`).\n\n### What do you see instead?\n\nAn average time spent per test of 185ms vs 96ms.\n\n### Additional information\n\nI tried running with/without additional options (f.e. `--test-coverage-exclude`, `--test-coverage-include`, `--test-coverage-branches`, `--test-coverage-functions`, `--test-coverage-lines`) but it didn't help. The performance issue seems only to be related to the algorithm that's triggered by the `--experimental-test-coverage` option.","author":{"url":"https://github.com/rozzilla","@type":"Person","name":"rozzilla"},"datePublished":"2024-09-24T15:50:16.000Z","interactionStatistic":{"@type":"InteractionCounter","interactionType":"https://schema.org/CommentAction","userInteractionCount":10},"url":"https://github.com/55103/node/issues/55103"}