logging.disable('WARN') breaks AsyncIO

[OverLordGoldDragon]

BPO	42644
Nosy	@asvetlov, @masklinn, @1st1, @Carreau, @miss-islington, @OverLordGoldDragon
PRs	bpo-42644: Validate values in logging.disable() #23786 [3.9] bpo-42644: Validate values in logging.disable() (GH-23786) #23796 [3.8] bpo-42644: Validate values in logging.disable() (GH-23786) #23797

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

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GitHub fields:

assignee = None
closed_at = <Date 2020-12-16.10:51:05.586>
created_at = <Date 2020-12-15.10:00:46.185>
labels = ['3.8', 'type-bug', 'library', '3.9', '3.10']
title = "logging.disable('WARN') breaks AsyncIO"
updated_at = <Date 2020-12-16.10:51:05.586>
user = 'https://github.com/OverLordGoldDragon'

bugs.python.org fields:

activity = <Date 2020-12-16.10:51:05.586>
actor = 'asvetlov'
assignee = 'none'
closed = True
closed_date = <Date 2020-12-16.10:51:05.586>
closer = 'asvetlov'
components = ['Library (Lib)']
creation = <Date 2020-12-15.10:00:46.185>
creator = 'OverLordGoldDragon'
dependencies = []
files = []
hgrepos = []
issue_num = 42644
keywords = ['patch']
message_count = 10.0
messages = ['383040', '383053', '383056', '383061', '383083', '383085', '383086', '383130', '383133', '383134']
nosy_count = 6.0
nosy_names = ['asvetlov', 'xmorel', 'yselivanov', 'mbussonn', 'miss-islington', 'OverLordGoldDragon']
pr_nums = ['23786', '23796', '23797']
priority = 'normal'
resolution = 'fixed'
stage = 'resolved'
status = 'closed'
superseder = None
type = 'behavior'
url = 'https://bugs.python.org/issue42644'
versions = ['Python 3.8', 'Python 3.9', 'Python 3.10']

[OverLordGoldDragon]

import logging
with logging.disable('WARN'): pass

See: ipython/ipython#12713
I'm not actually sure what's happening here, just reporting.

[asvetlov]

Reporting what? Please elaborate.

[OverLordGoldDragon]

Everything's in the linked issue; in summary, the command kills IPython, and an IPython maintainer showed code suggesting the problem's rooted in CPython's improper handling of 'WARN' as alias for logging.WARN.

[masklinn]

The problem seems to be in the user code? As you were told by "Carreau", loggin.disable takes a logging level (an integer), since you're giving it a string which it dutifully stores, it blows up at the next logging call which happens to be in asyncio.

This is not an asyncio bug, nor is it a crash anymore than passing a broken key function to sorted is a Python crash.

At most it's an enancement request: logging.disable could raise a TypeError immediately or convert the value to a loglevel the way setLevel does instead of storing the broken value as-is (all it does currently is store the value it receives on the root logger without any check).

[Carreau]

I should have been more careful in my explanation in the upstream issue to have a complete report in here.

I think that patching logging.disable to raise a type error immediately would be welcome; as the effect of storing a wrong type make any asyncio application fails in place that can be relatively remote from the location of the erroneous value, and could be quite hard to debug in other circumstances.

[masklinn]

I think that patching logging.disable to raise a type error immediately would be welcome

FWIW logging has a built-in checker / converter[0] which is already used in a bunch of places (e.g. the aforementioned setLevel), it could just be added inside disable in the same way it's used in setLevel[1] and would uniformly convert "level names" to proper levels or raise an error. That seems like a really easy patch / contribution.

[0] https://github.com/python/cpython/blob/3.9/Lib/logging/__init__.py#L189

[1] https://github.com/python/cpython/blob/3.9/Lib/logging/__init__.py#L906

[masklinn]

Oh I now see you've created a PR to do essentially that, nm.

[asvetlov]

New changeset b32d8b4 by Matthias Bussonnier in branch 'master':
bpo-42644: Validate values in logging.disable() (bpo-23786)
b32d8b4

[miss-islington]

New changeset 0a24a57 by Miss Islington (bot) in branch '3.8':
bpo-42644: Validate values in logging.disable() (GH-23786)
0a24a57

[miss-islington]

New changeset db63da7 by Miss Islington (bot) in branch '3.9':
bpo-42644: Validate values in logging.disable() (GH-23786)
db63da7