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?

Yeah, getaddrinfo isn't actually cancellable (because it's a blocking call that has to be run in a thread), but it's side-effect-free so if the user requests that it be cancelled then it's safe to return immediately while it keeps running in the background, and asyncio does so. But if we've already decided to discard the result then it's better to do that silently, like you say. When trio hits this case, it does silently throw away the result: https://github.com/python-trio/trio/blob/aebb42888dd0978c3b74f8c9cdf8aec2ce2cbd73/trio/_threads.py#L372-L377 It's a little bit more obvious in trio's case because there we 100% know that if the call to `trio.run` has finished, then there's no-one listening for the result, and that the user has explicitly requested this behavior. In asyncio's case, I guess in *theory* someone could still be hoping the Future's done callback will be invoked even after the loop is closed. This seems unlikely though... and in general when the loop is closed then every other registered callback is silently discarded, so doing that for run_in_executor seems fine too.

 New changeset bba2ba180de91177a73d28551dce71696d472c47 by Benjamin Peterson (Steve Dower) in branch '2.7': bpo-33148: Update Windows build to use OpenSSL 1.0.2o https://github.com/python/cpython/commit/bba2ba180de91177a73d28551dce71696d472c47