I'm attempting to perform the following actions multiple times in a single process with CPython 3.8.2:

1) Initialize an interpreter using the PEP-587 APIs.
2) Call Py_RunMain() (which finalizes the interpreter).

However, I've encountered at least 2 crashes due to use-after-free or unchecked NULL access (due to apparent state getting funky).

Are multiple interpreters / Py_RunMain() calls in a single process supported? Should I file bugs for all of the crashes I encounter?

Actually, I can reproduce the crash without Py_RunMain(). So I don't think the crash is related to the additional cleanup that Py_RunMain() does in addition to Py_FinalizeEx().

But I'd like to keep this issue open to track the original question about expected behavior.

I never tried, but I expect that the following pattern is fine:

for (i=0; i<5; i++) {
    Py_Initialize(); Py_RunMain()
}

Maybe Py_RunMain() must fail with a fatal error if it's called when Python is not initialized.

Since Py_RunMain() finalizes Python, you cannot call it multiple times without calling Py_Initialize() between calls.

Is there anything to do on this issue? Gregory, perhaps you could report the crashes you see so they can be evaluated?

> I'm attempting to perform the following actions multiple times in a single process with CPython 3.8.2:

test_embed already has test_repeated_init_and_inittab() test which runs Py_InitializeFromConfig() + Py_RunMain() multiple times.

I wrote an even more explicit test in PR 28466. I tested it manually on Python 3.9, 3.10 and 3.11: it works as expected.

Python 3.8 no longer accepts bugfixes. I close the issue as outdated.

Gregory: if you can still reproduce your issue on a supported Python version, please provide a reproducer.
devguide.python.org/#status-of-python-branches

New changeset 5e2c32e08ed77081cabd9d51f0589f81c1572732 by Victor Stinner in branch 'main':
bpo-40413: test_embed tests calling Py_RunMain() multiple times (GH-28466)
https://github.com/python/cpython/commit/5e2c32e08ed77081cabd9d51f0589f81c1572732

New changeset 3d16fc90ce36acaa846ee88bdd124f84d49395b3 by Miss Islington (bot) in branch '3.10':
bpo-40413: test_embed tests calling Py_RunMain() multiple times (GH-28466)
https://github.com/python/cpython/commit/3d16fc90ce36acaa846ee88bdd124f84d49395b3

New changeset 29e431419a0c23340099a9cd8cf23ec9c7788879 by Miss Islington (bot) in branch '3.9':
bpo-40413: test_embed tests calling Py_RunMain() multiple times (GH-28466) (GH-28471)
https://github.com/python/cpython/commit/29e431419a0c23340099a9cd8cf23ec9c7788879

I can't remember the circumstances of me reproducing this. The added test demonstrating that the interpreter can be initialized/finalized within a single process seems like a reasonable solution to ensure this is supported.