Incremental GC does not collect garbage as soon as expected

Bug report

Bug description:

This was found by @Yhg1s . If you run tests with this command:

./python -m test --randseed=3169227856 --no-randomize --single-process test_pyclbr test_trace test_pdb test_iter test_ordered_dict test_urllib2_localnet test_array test_generated_cases test_typing test_fnmatch test_tools test_descr test___all__ test_xml_dom_xmlbuilder test_nturl2path test_hmac test_pickle test_android test_ipaddress test_modulefinder test_interpreters test_zoneinfo test_runpy test_sqlite3 test_bdb test_zipfile test_crossinterp test_pulldom test_pkgutil test_re test_dbm_sqlite3 test_venv test_pyrepl test_xml_etree_c test_gc

The test_gc unit test fails with:

  File "/home/thomas/python/python/main/Lib/contextlib.py", line 85, in inner
    return func(*args, **kwds)
  File "/home/thomas/python/python/main/Lib/test/test_gc.py", line 1573, in test_bug1055820d
    self.fail("gc didn't happen after 50000 iterations")
    ~~~~~~~~~^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
AssertionError: gc didn't happen after 50000 iterations

Reverting GH-140262 seems to fix this. It is possible this is related to GH-141890 as well.

CPython versions tested on:

CPython main branch

Operating systems tested on:

Linux

Linked PRs

• gh-142001

从 test/test_gc.py 开始，尤其是 test_bug1055820d，并使用报告中的命令复现失败。将行为与回退 GH-140262 后的行为进行比较，并调查其与 GH-141890 可能存在的关系。当测试不再报告垃圾回收在 50,000 次迭代后失败时，即表示完成。