[openstack-dev] A new nova service? nova-periodic?

Michael Still mikal at stillhq.com
Tue Jan 15 20:54:23 UTC 2013

On Wed, Jan 16, 2013 at 1:06 AM, Sandy Walsh <sandy.walsh at rackspace.com> wrote:
> On 11/19/2012 10:57 PM, Michael Still wrote:
>> What do people think about adding another nova service which runs beside
>> nova-compute and runs periodic tasks which don't need any sort of shared
>> global state with nova-compute? We could do it with a flag so that the
>> default remains to use nova-compute for these periodic tasks, but if you
>> "opt in" they're done with a nova-periodic instead.
>> Thoughts?
> Wouldn't there be a problem with VM state management?
> The compute manager runs on the premise that it's essentially single
> threaded. If we have another process doing things in parallel we'll have
> to move the state verification to another location (the conductor?)

I think we start with periodic tasks which don't use any internal data
structures (image cache management is an example). Those are
effectively cron jobs that nova-compute runs because we don't have
another way to run them. We can worry about other periodic tasks later
if we decide we want to move them.


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