Encourage creation of aiohttp public objects inside a coroutine

[zhangyunhao116]

Replace asyncio.get_event_loop() with get_running_loop()

Nope

Nope

#3331

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[zhangyunhao116]

May be i should rebase those two commits for test ? @asvetlov

[gyermolenko]

@ZYunH towncrier fails on python 3.6, asyncio.get_event_loop() was added in 3.7. Maybe that's the case.
Also you can run flake8 aiohttp to resolve build failure for linter.

[zhangyunhao116]

@gyermolenko thx! i will fix this case

[asvetlov]

The idea is replacing the entire if loop is None block with self._loop = get_running_loop(loop).
The change doesn't only remove several lines but always check a loop (explicit or implicit) for running.

Please apply it everywhere.

[zhangyunhao116]

Got you.I will do this.
BTW,is there any plan to use asyncio.get_running_loop() which is a new api in python3.7 ?

[asvetlov]

Eventually yes, but we should support Python 3.5 and 3.6 for a long time

[zhangyunhao116]

I think it is simple at first, but it is wrong.There is still a lot of work to be done for test infra.Is there any easy way to make the test infra(more than 200 DeprecationWarning in test suites)?
And also, get event loop form another module make something wrong, i guess it create loop from other threads(i.e test.connector.test_ctor_loop()) or might I got that wrong. @asvetlov

[asvetlov]

Test suite disables default event loop, this is why you see RuntimeError: There is no current event loop in thread 'MainThread'.

In general converting def test_xxx() into async def test_xxx() can solve the issue.
Sometimes it is not easy.

Please fix trivial cases and let me know, I'll pick up the PR and finish it if needed.

[zhangyunhao116]

@asvetlov Thanks for reply! Now these commits only do

1. Add get_running_loop() in helpers.py
2. Replace asyncio.get_event_loop() with get_running_loop() in aiottp/*.py
   except two files:
   abc.py -> Replace will cause circular import error
   web.py -> run_app() is not coroutine function, and will always make warning

No unit tests for the changes

[asvetlov]

1. Extract AccessLog into a separate module #3336 should help with circular imports.
2. You are right, run_app() should keep using get_event_loop()

[zhangyunhao116]

Now i can't access this PR, because previous fork is deleted for next fix.Pick up this PR if you need.
Thanks for all the work, and very nice product!

[asvetlov]

Done in a separate commit

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