Discourage using fire-and-forget approach for creating new tasks

[asvetlov]

Recently I saw several questions on StackOverflow about complaining: asyncio swallows a raised exception when a code is executed inside new task.

I could collect exact links to SO issues but the problem is obvious: newbies are tending to create a new task but never do await task at the end.

As result exceptions raised by a task are not displayed at all.

PYTHONASYNCIODEBUG=x definitely helps to find a not awaited (aka not joined if you are prefer threading terms) task but the doc is not clear about the issue.

Maybe warning section for loop.create_task doc will help but I honestly have no idea how write the warning text.

Suggestions?

[1st1]

Don't we have Task.__del__ that always complaints about unhandled exceptions?

[Martiusweb]

Isn't it related to the conversation in #397 ?

[asvetlov]

Yes, #397 has a good example for the issue.
Other thing is that warning raised by Task.__del__ is very often just ignored as "no related to the problem" because it's raised later.
Honestly I don't know what to do here except adding a doc sentence like "A created task should be awaited somewhere later".