> Wow. I can reproduce refleaks in test_typing, but not in test_functools. This is weird. Indeed, I copied the new test from test_functools to test_typing, but now I see that pure Python version of lru_cache fails even if I remove this test and test that was previously failing with C version (test_extended_generic_rules_eq). > Not so sure, a refleak in pure-python version kind of scares me. It can be a bug in the core. Indeed. Now we need to figure out what it so special about typing that triggers the leak.