Bug report

Bug description:

As of 01dceba, I'm seeing a test failure on macOS and iOS in the tests/test_optimizer.py test case.

If you run the test by itself, (python -m test tests/test_optimizer.py) it passes.

However, if you run the entire test suite in default (alphabetical) order, it fails:

test test_optimizer failed -- Traceback (most recent call last):
  File "/Users/rkm/projects/python/host/lib/python3.13/test/test_optimizer.py", line 52, in test_builtin_dict
    self.assertEqual(
    ~~~~~~~~~~~~~~~~^
        orig_counter + 1,
        ^^^^^^^^^^^^^^^^^
        _testinternalcapi.get_rare_event_counters()["builtin_dict"]
        ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
    )
    ^
AssertionError: 256 != 255

test_optimizer failed (1 failure)

== Tests result: FAILURE ==

I've been able to narrow down a minimal reproduction case if you run the following sequence of tests:

python -m test test_fileinput test_funcattrs test_functools test_generators test_genexps test_getopt test_gettext test_optimizer

If you remove any one of the tests before test_optimizer, the test passes.

I'm observing the failure on both x86_64 (Ventura 13.5.2) and M1 (Ventura 13.6.2) hardware.

CPython versions tested on:

CPython main branch

Operating systems tested on:

macOS, Other

Linked PRs

• gh-115058: Add reset_rare_event_counters function in _testinternalcapi #115128