Support --boxed on Windows

I am developing a C/C++ module for Python (3.6 64-bit) under Windows, and would like to use the pytest + xdist framework to write tests for it. Each test should run in its own process, in case there is a crash in one of the tests. xdist supports this with the --boxed option, but unfortunately this does not work under Windows (as xdist uses os.fork provided by _process/forkedfunc.py to spawn subprocesses).

I tried extending this using the multiprocessing package, but without success so far. It requires serializing the pytest.Item object (multiprocessing uses pickle to exchange functions and objects between processes), which seems far from simple given its complexity. My idea is to convert pytest.Item to a serializable object (e.g. SerializableItem), which can be used to generate a proper pytest.Item in the subprocess. I got as far as reaching the Pytest runner with the generated Item, but I am stuck with generating pytest.Item._request.
Has anyone tried a similar approach? Maybe it is the wrong way to go given the complexity of the Item class.

I also tried to serialize pytest.Item using dill, which went much further than pickle, but the whole object could not be serialized (some part of the pytest.Config as far as I can tell).

Any help with this would be very welcome :-)

Start with _process/forkedfunc.py and the existing --boxed path, then review how pytest.Item and its _request are handled across processes. The issue’s proposed multiprocessing and serialization approaches are exploratory; done would mean --boxed supports running each test in its own process on Windows.