If you apply attached logging.patch, Python crash using attached crash.py:

$ echo|./python -i crash.py
>>>
>>> 
python: Python/_warnings.c:872: setup_context: Assertion `globals != NULL' failed.
Abandon (core dumped)


Attached logging.patch is a fix for bpo-26789: logging.FileHandler keeps a reference to the builtin open() function.

Attached crash.py does crash because of an unclosed file. It happens after PyInterpreterState_Clear(), in finalize_interp_clear():

    /* Last explicit GC collection */
    _PyGC_CollectNoFail();

setup_context() of Python/_warings.c does crash because tstate->interp->sysdict is NULL at this point.

Moreover, _io.TextIOWrapper.__init__() fails to import the locale module (to call locale.getpreferredencoding(), since the encoding is None) and picks the "ascii" encoding.

Moreover, even if I work around all these issues, _warnings.showwarnings() logs "lost sys.stderr" into stderr because, again, tstate->interp->sysdict is NULL at this point (and so sys.stderr no longer exists).

It looks like a bug in finalize_interp_clear() which triggers a garbage collection, whereas Python is no longer usable.

--

The logging module does automatically close files at exit using:

   atexit.register(shutdown)

But crash.py, a new file is opened by a logging handler after logging.shutdown() is called. Maybe another problem is that the logging module does not clear logger handlers, or prevent handlers to log more message, after shutdown() is called.

New changeset 8b3414818f5289eac530bf38bcfbd7b2b851805c by Victor Stinner in branch 'master':
bpo-42208: Pass tstate to _PyGC_CollectNoFail() (GH-23038)
https://github.com/python/cpython/commit/8b3414818f5289eac530bf38bcfbd7b2b851805c

New changeset dff1ad509051f7e07e77d1e3ec83314d53fb1118 by Victor Stinner in branch 'master':
bpo-42208: Move _PyImport_Cleanup() to pylifecycle.c (GH-23040)
https://github.com/python/cpython/commit/dff1ad509051f7e07e77d1e3ec83314d53fb1118

New changeset b9ee4af4c643a323779fd7076e80b29d611f2709 by Victor Stinner in branch 'master':
bpo-42208: Fix test_gdb for gc_collect_main() name (GH-23041)
https://github.com/python/cpython/commit/b9ee4af4c643a323779fd7076e80b29d611f2709

> bpo-42208: Pass tstate to _PyGC_CollectNoFail() (GH-23038)
> https://github.com/python/cpython/commit/8b3414818f5289eac530bf38bcfbd7b2b851805c

This change renames collect() to gc_collect_main(). It broke test_gdb on buildbots, whereas test_gdb passed on Travis CI on my PR 23038. Also, test_gdb is skipped on the Ubuntu job of GitHub Action since gdb is not installed. I created https://github.com/python/core-workflow/issues/383 to add gdb to Ubuntu dependencies. My PR 23043 adds gdb dependency.

New changeset eba5bf2f5672bf4861c626937597b85ac0c242b9 by Victor Stinner in branch 'master':
bpo-42208: Call GC collect earlier in PyInterpreterState_Clear() (GH-23044)
https://github.com/python/cpython/commit/eba5bf2f5672bf4861c626937597b85ac0c242b9

New changeset 09c6120be8c70366495b027ae3daa213609de3ed by Miss Skeleton (bot) in branch '3.9':
 bpo-42208: GitHub Action: Add gdb to posix dependencies (GH-23043) (GH-23047)
https://github.com/python/cpython/commit/09c6120be8c70366495b027ae3daa213609de3ed

> This change renames collect() to gc_collect_main(). It broke test_gdb on buildbots, whereas test_gdb passed on Travis CI on my PR 23038. Also, test_gdb is skipped on the Ubuntu job of GitHub Action since gdb is not installed. I created https://github.com/python/core-workflow/issues/383 to add gdb to Ubuntu dependencies. My PR 23043 adds gdb dependency.

Fixed by:

commit 6e03c0ad156797cd6e9132e895d55dac0344d340 (upstream/master, master)
Author: Victor Stinner <vstinner@python.org>
Date:   Fri Oct 30 22:52:30 2020 +0100

    GitHub Action: Add gdb to posix dependencies (GH-23043)
    
    Sort also dependencies and remove duplicates (liblzma-dev).

New changeset 710e82630775774dceba5e8f24b1b10e6dfaf9b7 by Victor Stinner in branch 'master':
bpo-42208: Add _Py_GetLocaleEncoding() (GH-23050)
https://github.com/python/cpython/commit/710e82630775774dceba5e8f24b1b10e6dfaf9b7

New changeset b62bdf71ea0cd52041d49691d8ae3dc645bd48e1 by Victor Stinner in branch 'master':
bpo-42208: Add _locale._get_locale_encoding() (GH-23052)
https://github.com/python/cpython/commit/b62bdf71ea0cd52041d49691d8ae3dc645bd48e1

I fixed all issues which prevented to fix bpo-26789, I close thie issue.