gh-111968: Use per-thread freelists for generator in free-threading

[corona10]

• Issue: Use per-thread freelists in --disable-gil builds #111968

[colesbury]

LGTM

[colesbury]

@corona10, only tangentially related to this PR, but in PyThreadState_Clear(), I think we want to call _Py_ClearFreeLists(freelist_state, 1); -- I think we want to finalize the free-lists in PyThreadState_Clear() so that they aren't used (and memory leaked) later on during the thread exit process.

cpython/Python/pystate.c

Line 1552 in 2d3f6b5

_Py_ClearFreeLists(freelist_state, 0);

[bedevere-bot]

⚠️⚠️⚠️ Buildbot failure ⚠️⚠️⚠️

Hi! The buildbot AMD64 Ubuntu NoGIL 3.x has failed when building commit 7fa511b.

What do you need to do:

1. Don't panic.
2. Check the buildbot page in the devguide if you don't know what the buildbots are or how they work.
3. Go to the page of the buildbot that failed (https://buildbot.python.org/all/#builders/1225/builds/1204) and take a look at the build logs.
4. Check if the failure is related to this commit (7fa511b) or if it is a false positive.
5. If the failure is related to this commit, please, reflect that on the issue and make a new Pull Request with a fix.

You can take a look at the buildbot page here:

https://buildbot.python.org/all/#builders/1225/builds/1204

Failed tests:

• test.test_concurrent_futures.test_process_pool
• test_tools
• test.test_multiprocessing_spawn.test_misc
• test_perf_profiler
• test_math

Failed subtests:

• test_wait_integer - test.test_multiprocessing_spawn.test_misc.TestWait.test_wait_integer
• test_map_timeout - test.test_concurrent_futures.test_process_pool.ProcessPoolSpawnProcessPoolExecutorTest.test_map_timeout
• test_sys_api_with_existing_trampoline - test.test_perf_profiler.TestPerfTrampoline.test_sys_api_with_existing_trampoline

Summary of the results of the build (if available):

==

Click to see traceback logs

Traceback (most recent call last):
  File "/home/ubuntu/buildarea/3.x.itamaro-ubuntu-aws.nogil/build/Lib/test/test_perf_profiler.py", line 48, in tearDown
    file.unlink()
    ~~~~~~~~~~~^^
  File "/home/ubuntu/buildarea/3.x.itamaro-ubuntu-aws.nogil/build/Lib/pathlib/__init__.py", line 763, in unlink
    os.unlink(self)
    ~~~~~~~~~^^^^^^
FileNotFoundError: [Errno 2] No such file or directory: '/tmp/perf-2445732.map'


Traceback (most recent call last):
  File "/home/ubuntu/buildarea/3.x.itamaro-ubuntu-aws.nogil/build/Lib/test/_test_multiprocessing.py", line 5136, in test_wait_integer
    self.assertLess(delta, expected + 2)
    ~~~~~~~~~~~~~~~^^^^^^^^^^^^^^^^^^^^^
AssertionError: 5.792868422344327 not less than 5


Traceback (most recent call last):
  File "/home/ubuntu/buildarea/3.x.itamaro-ubuntu-aws.nogil/build/Lib/test/test_concurrent_futures/executor.py", line 69, in test_map_timeout
    self.assertEqual([None, None], results)
    ~~~~~~~~~~~~~~~~^^^^^^^^^^^^^^^^^^^^^^^
AssertionError: Lists differ: [None, None] != []