class member varibles assigned member functions create a circular reference

[cliffcordeiro]

BPO	44857

^{Note: these values reflect the state of the issue at the time it was migrated and might not reflect the current state.}

Show more details

GitHub fields:

assignee = None
closed_at = <Date 2021-08-07.02:34:55.458>
created_at = <Date 2021-08-07.02:20:59.937>
labels = ['interpreter-core', 'invalid', '3.8', 'performance']
title = 'class member varibles assigned member functions create a circular reference'
updated_at = <Date 2021-08-07.02:34:55.457>
user = 'https://bugs.python.org/cliffcordeiro'

bugs.python.org fields:

activity = <Date 2021-08-07.02:34:55.457>
actor = 'cliff.cordeiro'
assignee = 'none'
closed = True
closed_date = <Date 2021-08-07.02:34:55.458>
closer = 'cliff.cordeiro'
components = ['Interpreter Core']
creation = <Date 2021-08-07.02:20:59.937>
creator = 'cliff.cordeiro'
dependencies = []
files = []
hgrepos = []
issue_num = 44857
keywords = []
message_count = 2.0
messages = ['399165', '399166']
nosy_count = 1.0
nosy_names = ['cliff.cordeiro']
pr_nums = []
priority = 'normal'
resolution = 'not a bug'
stage = 'resolved'
status = 'closed'
superseder = None
type = 'resource usage'
url = 'https://bugs.python.org/issue44857'
versions = ['Python 3.8']

[cliffcordeiro]

This class is not collected by the gc without a custom __del__ method to del or assign None to self.fn:

import gc

class Leak:
    def __init__(self):
        self.fn = self.x

    def x(self):
        pass


gc.set_debug(gc.DEBUG_SAVEALL)

l = Leak()
del l
gc.collect()

for item in gc.garbage:
    print(item)

[cliffcordeiro]

It looks like the collector does detect the cycle and that's why it ends up in garbage with gc.DEBUG_SAVEALL set. Sorry about that.