asyncio - run coroutine in the background

Frank Millman frank at chagford.com
Tue Feb 16 09:36:00 EST 2016


"Marko Rauhamaa"  wrote in message news:87d1rwpwo2.fsf at elektro.pacujo.net...
>
> Kevin Conway <kevinjacobconway at gmail.com>:
>
> > If you're handling coroutines there is an asyncio facility for
> > "background tasks". The ensure_future [1] will take a coroutine,
> > attach it to a Task, and return a future to you that resolves when the
> > coroutine is complete.
>
> Ok, yes, but those "background tasks" monopolize the CPU once they are
> scheduled to run.
>
> If your "background task" doesn't need a long time to run, just call the
> function in the foreground and be done with it. If it does consume time,
> you need to delegate it to a separate process so the other tasks remain
> responsive.
>

I will explain my situation - perhaps you can tell me if it makes sense.

My background task does take a long time to run - about 10 seconds - but 
most of that time is spent waiting for database responses, which is handled 
in another thread.

You could argue that the database thread should rather be handled by another 
process, and that is definitely an option if I find that response times are 
affected.

So far my response times have been very good, even with database activity in 
the background. However, I have not simulated a large number of concurrent 
users. That could throw up the kinds of problem that you are concerned 
about.

Frank




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