Memory leak when defining a new class inside a loop

[pavloskallis]

BPO	40292
Nosy	@rhettinger, @serhiy-storchaka
Files	memory_leak.py: Script to reproduce the memory leak

^{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 2020-04-15.10:20:14.394>
created_at = <Date 2020-04-15.08:36:26.438>
labels = ['3.8', '3.9', 'performance', 'expert-C-API', '3.7', 'invalid']
title = 'Memory leak when defining a new class inside a loop'
updated_at = <Date 2020-04-15.10:20:14.391>
user = 'https://bugs.python.org/pavloskallis'

bugs.python.org fields:

activity = <Date 2020-04-15.10:20:14.391>
actor = 'serhiy.storchaka'
assignee = 'none'
closed = True
closed_date = <Date 2020-04-15.10:20:14.394>
closer = 'serhiy.storchaka'
components = ['C API']
creation = <Date 2020-04-15.08:36:26.438>
creator = 'pavlos kallis'
dependencies = []
files = ['49062']
hgrepos = []
issue_num = 40292
keywords = []
message_count = 3.0
messages = ['366495', '366503', '366504']
nosy_count = 3.0
nosy_names = ['rhettinger', 'serhiy.storchaka', 'pavlos kallis']
pr_nums = []
priority = 'normal'
resolution = 'not a bug'
stage = 'resolved'
status = 'closed'
superseder = None
type = 'resource usage'
url = 'https://bugs.python.org/issue40292'
versions = ['Python 3.5', 'Python 3.6', 'Python 3.7', 'Python 3.8', 'Python 3.9']

[pavloskallis]

Running the script, memory starts to leak and garbage count increases.

Running the same script in python 2.7 does not cause the memory leak.

[rhettinger]

Python2.7 gives similar results with:

    class A(object):
        pass

[serhiy-storchaka]

It is not a leak. It is expected behavior when you call gc.set_debug(gc.DEBUG_SAVEALL).