This issue tracker has been migrated to GitHub, and is currently read-only.
For more information, see the GitHub FAQs in the Python's Developer Guide.

Author Ben.Darnell
Recipients Ben.Darnell, aeros, asvetlov, serhiy.storchaka, xtreak, yselivanov
Date 2021-05-29.17:45:20
SpamBayes Score -1.0
Marked as misclassified Yes
Message-id <>
> The maintenance burden of the introduced deprecation should be pretty low.

This is going to cause an unpleasant amount of churn in the Tornado community. It's been idiomatic (going back 12 years now) to do all your setup in synchronous code before starting the event loop. I'm tempted to restore the implicit loop creation in Tornado's `IOLoop.current()` (which is now essentially a wrapper around `asyncio.get_event_loop()`).

> It leads to weird errors when get_event_loop() is called at import-time and is used for asyncio code execution.

*Checks's implementation* Oh, I can see how that's a problem (and I've been giving people bad advice about the interchangeability of Tornado's IOLoop.run_sync and But why does `` unconditionally create a new event loop instead of running on `asyncio.get_event_loop`? If used asyncio.get_event_loop it seems to me that we'd have the expected behavior and wouldn't have to make breaking changes to get_event_loop. 

> Low-level new_event_loop()/loop.run_until_complete() are still present to run async code if top-level run() is not suitable for any reason.

What if you're using run_forever instead of run_until_complete? (this is the common mode of operation for Tornado) There are solutions, of course (my preferred one is `await asyncio.Event().wait()`), but it's an extra conceptual hurdle to throw at users in a "hello world" example and this is why I've stuck with the model that uses (the equivalent of) run_forever instead of
Date User Action Args
2021-05-29 17:45:20Ben.Darnellsetrecipients: + Ben.Darnell, asvetlov, serhiy.storchaka, yselivanov, xtreak, aeros
2021-05-29 17:45:20Ben.Darnellsetmessageid: <>
2021-05-29 17:45:20Ben.Darnelllinkissue39529 messages
2021-05-29 17:45:20Ben.Darnellcreate