René's URL Explorer Experiment

{"@context":"https://schema.org","@type":"DiscussionForumPosting","headline":"_lsprof.c: Profiler.enable() clobbers exception from use_tool_id","articleBody":"# Bug report\n\n### Bug description:\n\nOriginal gist: https://gist.github.com/devdanzin/ed7691a99c26ede561a549ab1dba00b2\n\n\u003e ## Summary\n\u003e \n\u003e In `Modules/_lsprof.c` (lines 821-823), when `sys.monitoring.use_tool_id()` fails, `PyErr_Format` unconditionally replaces the real exception with a generic ValueError.\n\u003e \n\u003e ## Fix\n\u003e \n\u003e Remove the `PyErr_Format` call and let the original exception propagate.\n\u003e \n\u003e ## Reproducer\n\u003e \n\u003e ```python\n\u003e import cProfile\n\u003e p1 = cProfile.Profile()\n\u003e p1.enable()\n\u003e p2 = cProfile.Profile()\n\u003e try:\n\u003e     p2.enable()  # ValueError: \"Another profiling tool is already active\"\n\u003e except ValueError as e:\n\u003e     print(f\"Generic message masks real error: {e}\")\n\u003e finally:\n\u003e     p1.disable()\n\u003e ```\n\n\n### CPython versions tested on:\n\nCPython main branch\n\n### Operating systems tested on:\n\n_No response_\n\n\u003c!-- gh-linked-prs --\u003e\n### Linked PRs\n* gh-153070\n* gh-153240\n* gh-153241\n* gh-153242\n\u003c!-- /gh-linked-prs --\u003e\n","author":{"url":"https://github.com/aisk","@type":"Person","name":"aisk"},"datePublished":"2026-07-05T07:02:15.000Z","interactionStatistic":{"@type":"InteractionCounter","interactionType":"https://schema.org/CommentAction","userInteractionCount":0},"url":"https://github.com/153068/cpython/issues/153068"}