[openstack-dev] Moving task flow to conductor - concern about scale

Dan Smith dms at danplanet.com
Tue Jul 16 13:51:02 UTC 2013

> In the original context of using Conductor as a database proxy then
> the number of conductor instances is directly related to the number
> of compute hosts I need them to serve. 

Just a point of note, as far as I know, the plan has always been to
establish conductor as a thing that sits between the api and compute
nodes. However, we started with the immediate need, which was the
offloading of database traffic.

> What I not sure is that I would also want to have the same number of
> conductor instances for task control flow - historically even running
> 2 schedulers has been a problem, so the thought of having 10's of
> them makes me very concerned at the moment.   However I can't see any
> way to specialise a conductor to only handle one type of request.

Yeah, I don't think the way it's currently being done allows for

Since you were reviewing actual task code, can you offer any specifics
about the thing(s) that concern you? I think that scaling conductor (and
its tasks) horizontally is an important point we need to achieve, so if
you see something that needs tweaking, please point it out.

Based on what is there now and proposed soon, I think it's mostly fairly
safe, straightforward, and really no different than what two computes do
when working together for something like resize or migrate.

> So I guess my question is, given that it may have to address two
> independent scale drivers, is putting task work flow and DB proxy
> functionality into the same service really the right thing to do - or
> should there be some separation between them.

I think that we're going to need more than one "task" node, and so it
seems appropriate to locate one scales-with-computes function with



More information about the OpenStack-dev mailing list