Missing Py_DECREF in task_step_impl() in _asynciomodule.c

[cjerdonek]

BPO	40559
Nosy	@asvetlov, @cjerdonek, @1st1, @miss-islington
PRs	bpo-40559: Add Py_DECREF to _asynciomodule.c:task_step_impl() #19990 [3.8] bpo-40559: Add Py_DECREF to _asynciomodule.c:task_step_impl() (GH-19990) #19995 [3.7] bpo-40559: Add Py_DECREF to _asynciomodule.c:task_step_impl() (GH-19990) #19996

^{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 2020-05-08.11:47:23.803>
created_at = <Date 2020-05-08.07:40:03.008>
labels = ['3.8', 'expert-asyncio', '3.7', '3.9', 'performance']
title = 'Missing Py_DECREF in task_step_impl() in _asynciomodule.c'
updated_at = <Date 2020-05-08.11:47:23.803>
user = 'https://github.com/cjerdonek'

bugs.python.org fields:

activity = <Date 2020-05-08.11:47:23.803>
actor = 'chris.jerdonek'
assignee = 'none'
closed = True
closed_date = <Date 2020-05-08.11:47:23.803>
closer = 'chris.jerdonek'
components = ['asyncio']
creation = <Date 2020-05-08.07:40:03.008>
creator = 'chris.jerdonek'
dependencies = []
files = []
hgrepos = []
issue_num = 40559
keywords = ['patch']
message_count = 5.0
messages = ['368425', '368426', '368432', '368433', '368434']
nosy_count = 4.0
nosy_names = ['asvetlov', 'chris.jerdonek', 'yselivanov', 'miss-islington']
pr_nums = ['19990', '19995', '19996']
priority = 'normal'
resolution = 'fixed'
stage = 'resolved'
status = 'closed'
superseder = None
type = 'resource usage'
url = 'https://bugs.python.org/issue40559'
versions = ['Python 3.7', 'Python 3.8', 'Python 3.9']

[cjerdonek]

There is a missing Py_DECREF in task_step_impl() in _asynciomodule.c:

cpython/Modules/_asynciomodule.c

Line 2641 in 02fa0ea

return NULL;

It should have the form:

    if (clear_exc) {
        Py_DECREF(exc);
    }

This was introduced here in 3.7:
bca4939

I'm not sure of the likelihood of this ever getting triggered (it appears to be unlikely), but it should still be addressed.

I will file a patch shortly.

[cjerdonek]

Here is the original issue: https://bugs.python.org/issue31185

[cjerdonek]

New changeset d2c349b by Chris Jerdonek in branch 'master':
bpo-40559: Add Py_DECREF to _asynciomodule.c:task_step_impl() (GH-19990)
d2c349b

[cjerdonek]

New changeset 0e4a5e9 by Miss Islington (bot) in branch '3.8':
[3.8] bpo-40559: Add Py_DECREF to _asynciomodule.c:task_step_impl() (GH-19990)
0e4a5e9

[cjerdonek]

New changeset 2501428 by Miss Islington (bot) in branch '3.7':
[3.7] bpo-40559: Add Py_DECREF to _asynciomodule.c:task_step_impl() (GH-19990)
2501428