[Openstack-operators] [nova] Looking for feedback on a spec to limit max_count in multi-create requests

Saverio Proto zioproto at gmail.com
Thu Oct 12 09:09:52 UTC 2017


Hello Matt,

starting 1000 instances in production works for me already. We are on
Openstack Newton.
I described my configuration here:
https://cloudblog.switch.ch/2017/08/28/starting-1000-instances-on-switchengines/

If things blow up for you with hundreds, probably there is a
regression somewhere.

Thanks

Saverio


2017-10-06 23:43 GMT+02:00 Matt Riedemann <mriedemos at gmail.com>:
> I've been chasing something weird I was seeing in devstack when creating
> hundreds of instances in a single request where at some limit, things blow
> up in an unexpected way during scheduling and all instances were put into
> ERROR state. Given the environment I was running in, this shouldn't have
> been happening, and today we figured out what was actually happening. To
> summarize, we retry scheduling requests on RPC timeout so you can have
> scheduler_max_attempts greenthreads running concurrently trying to schedule
> 1000 instances and melt your scheduler.
>
> I've started a spec which goes into the details of the actual issue:
>
> https://review.openstack.org/#/c/510235/
>
> It also proposes a solution, but I don't feel it's the greatest solution, so
> there are also some alternatives in there.
>
> I'm really interested in operator feedback on this because I assume that
> people are dealing with stuff like this in production already, and have had
> to come up with ways to solve it.
>
> --
>
> Thanks,
>
> Matt
>
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