warnings.catch_warnings is async-unsafe #91505
Description
import warnings import asyncio async def spam(): with warnings.catch_warnings(record=True) as ws: await asyncio.sleep(0.1) w = Warning("12345") warnings.warn(w) assert w in (ww.message for ww in ws) async def ham(): with warnings.catch_warnings(record=True) as ws: await asyncio.sleep(0.2) async def main(): await asyncio.gather(spam(), ham()) asyncio.run(main())Despite technically being documented (https://docs.python.org/3/library/warnings.html#warnings.catch_warnings), this is very error-prone, surprising and not at all useful. The warnings module should probably use contextvars to manage the warning handler.