Bug report
Bug description:
This is an old issue but it has become more urgent to fix given free-threaded Python. A simple example to show how the current context manager can fail:
from concurrent.futures import ThreadPoolExecutor
import warnings
def test_warning():
with warnings.catch_warnings():
warnings.simplefilter("ignore")
warnings.warn("my warning", UserWarning)
tpe = ThreadPoolExecutor(max_workers=10)
threads = [tpe.submit(test_warning) for _ in range(100)]
[t.result() for t in threads]
Since test_warning() is running in separate threads, there is no consistent ordering of which context manager exits first. That means the filters value that gets restored is also not consistent (a race between the threads about which version of the filters value they will restore).
The context manager is also not friendly to async code. These issues have been reported before:
The fairly obvious fix to this issue is to use contextvars, similar to how the decimal module uses a context. This is both thread safe and friendly to async code.
The warnings module itself has some "shallow" thread safety issues but these are relatively easy to fix and no API changes are needed.
CPython versions tested on:
CPython main branch
Operating systems tested on:
Linux
Linked PRs
Bug report
Bug description:
This is an old issue but it has become more urgent to fix given free-threaded Python. A simple example to show how the current context manager can fail:
Since
test_warning()is running in separate threads, there is no consistent ordering of which context manager exits first. That means the filters value that gets restored is also not consistent (a race between the threads about which version of the filters value they will restore).The context manager is also not friendly to async code. These issues have been reported before:
The fairly obvious fix to this issue is to use
contextvars, similar to how thedecimalmodule uses a context. This is both thread safe and friendly to async code.The
warningsmodule itself has some "shallow" thread safety issues but these are relatively easy to fix and no API changes are needed.CPython versions tested on:
CPython main branch
Operating systems tested on:
Linux
Linked PRs