Reference leak for object with non-trivial finalizer

[efimov-mikhail]

Bug report

Bug description:

If we put this code snippet to Lib/test/test_dict_user_leak.py

import unittest

class DictUser:
    def __init__(self, d: dict):
        self.d = d

    def __del__(self):
        self.d['a'] = DictUser(self.d)

class TestFinalizerLeak(unittest.TestCase):
    def test_dict_user(self):
        DictUser(dict())

if __name__ == '__main__':
    unittest.main()

then we can see leaks with the following command:
./python -m test -R 3:3 -v test_dict_user_leak

CPython versions tested on:

CPython main branch, 3.14, 3.13

Operating systems tested on:

Linux

[jamalhill1441-coder]

Lib/test/test_dict_user_leak.py

[colesbury]

I don't think this is a bug in Python. You are creating trash in in a finalizer that will only be collected on the next GC cycle.