[New-bugs-announce] [issue33148] RuntimeError('Event loop is closed') after cancelling getaddrinfo and closing loop

[Vitaly Kruglikov]

New submission from Vitaly Kruglikov <vitaly.krug at gmail.com>:

I see this exception on the terminal:
```
exception calling callback for <Future at 0x10722ee48 state=finished returned list>
Traceback (most recent call last):
  File "/usr/local/Cellar/python/3.6.4_3/Frameworks/Python.framework/Versions/3.6/lib/python3.6/concurrent/futures/_base.py", line 324, in _invoke_callbacks
    callback(self)
  File "/usr/local/Cellar/python/3.6.4_3/Frameworks/Python.framework/Versions/3.6/lib/python3.6/asyncio/futures.py", line 414, in _call_set_state
    dest_loop.call_soon_threadsafe(_set_state, destination, source)
  File "/usr/local/Cellar/python/3.6.4_3/Frameworks/Python.framework/Versions/3.6/lib/python3.6/asyncio/base_events.py", line 620, in call_soon_threadsafe
    self._check_closed()
  File "/usr/local/Cellar/python/3.6.4_3/Frameworks/Python.framework/Versions/3.6/lib/python3.6/asyncio/base_events.py", line 357, in _check_closed
    raise RuntimeError('Event loop is closed')
RuntimeError: Event loop is closed
```

When executing this code:
```
import asyncio

while True:
    loop = asyncio.new_event_loop()

    coro = loop.getaddrinfo('www.google.com', 80)

    task = asyncio.ensure_future(coro, loop=loop)

    task.cancel()

    loop.call_soon_threadsafe(loop.stop)

    loop.run_forever()

    loop.close()
```

Shouldn't a cancelled operation go away (or at least pretend to go away) cleanly?

----------
components: asyncio
messages: 314484
nosy: asvetlov, vitaly.krug, yselivanov
priority: normal
severity: normal
status: open
title: RuntimeError('Event loop is closed') after cancelling getaddrinfo and closing loop
versions: Python 3.6

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Python tracker <report at bugs.python.org>
<https://bugs.python.org/issue33148>
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