Don't ignore errors raised by `PyErr_WarnFormat` in `warn_about_fork_with_threads`
Instead, ignore the warnings in all test code that forks. (That's a lot of functions.)
In `test_support`, make `ignore_warnings` a context manager (as well as decorator),
and add a `message` argument to it.
Also add a `ignore_fork_in_thread_deprecation_warnings` helper for the deadlock-in-fork
warning.
Most importantly, this resolves the issues with functions and types defined in __main__.
It also expands the number of supported objects and simplifies the implementation.
The ProcessPoolForkserver combined with resource_tracker starts a thread
after forking, which is not supported by TSan.
Also skip test_multiprocessing_fork for the same reason
This builds on https://github.com/python/cpython/pull/106807, which adds
a return code to ResourceTracker, to make future debugging easier.
Testing this “in situ” proved difficult, since the global ResourceTracker is
involved in test infrastructure. So, the tests here create a new instance and
feed it fake data.
---------
Co-authored-by: Yonatan Bitton <yonatan.bitton@perception-point.io>
Co-authored-by: Yonatan Bitton <bityob@gmail.com>
Co-authored-by: Antoine Pitrou <antoine@python.org>
