Implement asyncio._get_running_loop() and get_event_loop() in C

[1st1]

BPO	32296
Nosy	@vstinner, @asvetlov, @ambv, @1st1
PRs	bpo-32296: Implement asyncio.get_event_loop and _get_running_loop in C. #4827 bpo-32296: Unbreak tests on Windows #4850 bpo-32296: Make get_running_loop() another 4-5x faster #5277

^{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 = 'https://github.com/1st1'
closed_at = <Date 2017-12-18.10:56:09.066>
created_at = <Date 2017-12-12.22:59:23.286>
labels = ['expert-asyncio', '3.7', 'performance']
title = 'Implement asyncio._get_running_loop() and get_event_loop() in C'
updated_at = <Date 2018-01-23.20:10:05.974>
user = 'https://github.com/1st1'

bugs.python.org fields:

activity = <Date 2018-01-23.20:10:05.974>
actor = 'yselivanov'
assignee = 'yselivanov'
closed = True
closed_date = <Date 2017-12-18.10:56:09.066>
closer = 'asvetlov'
components = ['asyncio']
creation = <Date 2017-12-12.22:59:23.286>
creator = 'yselivanov'
dependencies = []
files = []
hgrepos = []
issue_num = 32296
keywords = ['patch']
message_count = 6.0
messages = ['308169', '308237', '308247', '308253', '308261', '310520']
nosy_count = 4.0
nosy_names = ['vstinner', 'asvetlov', 'lukasz.langa', 'yselivanov']
pr_nums = ['4827', '4850', '5277']
priority = 'normal'
resolution = 'fixed'
stage = 'resolved'
status = 'closed'
superseder = None
type = 'performance'
url = 'https://bugs.python.org/issue32296'
versions = ['Python 3.7']

[1st1]

asyncio.get_event_loop(), and, subsequently asyncio._get_running_loop() are one of the most frequently executed functions in asyncio. They also can't be sped up by third-party event loops like uvloop.

When implemented in C they become 4x faster.

[1st1]

New changeset a70232f by Yury Selivanov in branch 'master':
bpo-32296: Implement asyncio.get_event_loop and _get_running_loop in C. (bpo-4827)
a70232f

[vstinner]

Hum, sometimes it's better to wait for AppVeyor :-) You broke all Windows buildbots! :-) Example:

http://buildbot.python.org/all/#/builders/40/builds/278

======================================================================
ERROR: test_get_event_loop_returns_running_loop (test.test_asyncio.test_events.TestCGetEventLoop)
----------------------------------------------------------------------

Traceback (most recent call last):
  File "C:\buildbot.python.org\3.x.kloth-win64\build\lib\test\test_asyncio\test_events.py", line 2738, in setUp
    watcher = asyncio.SafeChildWatcher()
AttributeError: module 'asyncio' has no attribute 'SafeChildWatcher'

======================================================================
ERROR: test_get_event_loop_returns_running_loop (test.test_asyncio.test_events.TestPyGetEventLoop)
----------------------------------------------------------------------

Traceback (most recent call last):
  File "C:\buildbot.python.org\3.x.kloth-win64\build\lib\test\test_asyncio\test_events.py", line 2738, in setUp
    watcher = asyncio.SafeChildWatcher()
AttributeError: module 'asyncio' has no attribute 'SafeChildWatcher'

[1st1]

Thanks Victor. I've made a PR to fix this.

[1st1]

New changeset bfbf04e by Yury Selivanov in branch 'master':
bpo-32296: Unbreak tests on Windows (bpo-4850)
bfbf04e

[1st1]

New changeset 9d411c1 by Yury Selivanov in branch 'master':
bpo-32296: Make get_running_loop() another 4-5x faster (bpo-5277)
9d411c1