weakref_leak_binary_test.py

import weakref, sys, gc

class C:
    def __add__(self, other): return NotImplemented
    def __radd__(self, other): return NotImplemented

obj = type('D', (), {})()
dead = weakref.proxy(obj)
del obj; gc.collect()

live_obj = C()
live = weakref.proxy(live_obj)

before = sys.gettotalrefcount()
for i in range(10000):
    try:
        live + dead
    except ReferenceError:
        pass
after = sys.gettotalrefcount()
print(f"Leaked {after - before} refs (~{(after-before)//10000}/call)")