"__del__" method sometimes doesn't run in time

[Locked-chess-official]

Bug report

Bug description:

 >>>class A:
 ...   def __del__(self):
 ...       print(f'object {id(self)} is deleted')
 ...        
>>>a = A()
>>>b = A()
>>>b.AA = a
>>>del a
>>>b.AA
<__main__.A object at 0x0000024720B18980>
>>>del b
object 2504514290384 is deleted
>>>c = A()
>>>0x0000024720B18980
object 2504514439552 is deleted
2504514439552
>>>a = A()
>>>b = A()
>>>b.AA = a
>>>del a
>>>1
1
>>>del b
object 2504514803344 is deleted
object 2504514603360 is deleted

In IDLE the "a.del" method began to run until the id of a was reprinted instead of "a" and "b" were deleted in the first condition, but in the second condition it doesn't run in the same way. I think that it should run in the same way because there's no other quote about "a" and "b".

CPython versions tested on:

3.13

Operating systems tested on:

Windows

[skirpichev]

This is not a bug and happens in ordinary CPython shell. According to docs:

Deletion of a name removes the binding of that name from the local or global namespace, depending on whether the name occurs in a global statement in the same code block. If the name is unbound, a NameError exception will be raised.

>>> class A:
...     def __del__(self):
...         print(f'object {id(self)} is deleted')
...         
>>> a = A()
>>> b = A()
>>> b.AA = a
>>> a
<__main__.A object at 0x7fa67a0f0ad0>
>>> b.AA
<__main__.A object at 0x7fa67a0f0ad0>
>>> del a  # this just delete binding, not object at 0x7fa67a0f0ad0
>>> b.AA
<__main__.A object at 0x7fa67a0f0ad0>
>>> import gc
>>> gc.collect()
31
>>> b.AA  # it's still accessible
<__main__.A object at 0x7fa67a0f0ad0>
>>> del b  # at this point everything can be garbage-collected
object 140352991193168 is deleted
>>> gc.collect()  # yes!
object 140352989104848 is deleted
0