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.