gh-118846: Fix free-threading test failures when run sequentially

[colesbury]

The free-threaded build currently immortalizes some objects once the first thread is started. This can lead to test failures depending on the order in which tests are run. This PR addresses those failures by suppressing immortalization or skipping the affected tests.

• Issue: Freethreading build fails -m test --pgo: test_ordered_dict and test_struct failed #118846

[colesbury]

@hroncok - this should address the remaining test failures in conjunction with #118862

[DinoV]

LGTM!

[hroncok]

I still have:

======================================================================
ERROR: test_builtin_with_more_than_four_children (test.test_pydoc.test_pydoc.PydocDocTest.test_builtin_with_more_than_four_children)
Tests help on builtin object which have more than four child classes.
----------------------------------------------------------------------
Traceback (most recent call last):
  File ".../cpython/Lib/test/test_pydoc/test_pydoc.py", line 537, in test_builtin_with_more_than_four_children
    text = doc.docclass(object)
  File ".../cpython/Lib/pydoc.py", line 1424, in docclass
    subclasses = sorted(
        (str(cls.__name__) for cls in type.__subclasses__(object)
         if not cls.__name__.startswith("_") and cls.__module__ == "builtins"),
        key=str.lower
    )
  File ".../cpython/Lib/pydoc.py", line 1426, in <genexpr>
    if not cls.__name__.startswith("_") and cls.__module__ == "builtins"),
                                            ^^^^^^^^^^^^^^
  File ".../cpython/Lib/test/test_inspect/test_inspect.py", line 775, in __module__
    raise AttributeError
AttributeError: . Did you mean: '__reduce__'?

----------------------------------------------------------------------
Ran 108 tests in 1.709s

FAILED (errors=1, skipped=3)
test test.test_pydoc.test_pydoc failed


======================================================================
FAIL: test_bug1055820c (test.test_gc.GCTogglingTests.test_bug1055820c)
----------------------------------------------------------------------
Traceback (most recent call last):
  File ".../cpython/Lib/test/test_gc.py", line 1361, in test_bug1055820c
    self.fail("gc didn't happen after 10000 iterations")
    ~~~~~~~~~^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
AssertionError: gc didn't happen after 10000 iterations

======================================================================
FAIL: test_bug1055820d (test.test_gc.GCTogglingTests.test_bug1055820d)
----------------------------------------------------------------------
Traceback (most recent call last):
  File ".../cpython/Lib/contextlib.py", line 85, in inner
    return func(*args, **kwds)
  File ".../cpython/Lib/test/test_gc.py", line 1429, in test_bug1055820d
    self.fail("gc didn't happen after 10000 iterations")
    ~~~~~~~~~^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
AssertionError: gc didn't happen after 10000 iterations

----------------------------------------------------------------------
Ran 49 tests in 14.476s

FAILED (failures=2, skipped=4)
test test_gc failed

Not sure if the pydoc thing is related, but the gc might.

[colesbury]

The pydoc failure is a funny interaction between tests. In test_inspect.py, we create a class that raises an error when you access __module__:

cpython/Lib/test/test_inspect/test_inspect.py

Lines 771 to 775 in 98ff3f6

	def test_getfile_class_without_module(self):
	class CM(type):
	@property
	def __module__(cls):
	raise AttributeError

In the free-threaded build, this class is now immortalized so it's still alive later on when test_pydoc tries to generate the pydoc for all subclasses of object.

[colesbury]

Ok, I think the test_pydoc and test_gc failures are fixed now too.

[miss-islington-app]

Thanks @colesbury for the PR 🌮🎉.. I'm working now to backport this PR to: 3.13.
🐍🍒⛏🤖

[bedevere-app]

GH-118927 is a backport of this pull request to the 3.13 branch.

[hroncok]

This is the only one I got now:

======================================================================
ERROR: test_expr_context (test.test_ast.ASTConstructorTests.test_expr_context)
----------------------------------------------------------------------
Traceback (most recent call last):
  File ".../cpython/Lib/test/test_ast.py", line 3042, in test_expr_context
    self.assertIsInstance(name.ctx, ast.Load)
                          ^^^^^^^^
AttributeError: 'Name' object has no attribute 'ctx'

----------------------------------------------------------------------
Ran 175 tests in 0.765s

FAILED (errors=1, skipped=1)

[colesbury]

Just checking, this is from ./python -m test -W on the 3.13 branch? Is it a debug build?

[AlexWaygood]

Note that that AST test was only merged (and backported to 3.13) yesterday in #118854

[hroncok]

I might have git pulled but forgot to rebuild it. Mea culpa. Trying fresh.

[hroncok]

All is good now, thank you!