[openstack-dev] [Heat] Using Job Queues for timeout ops

Ryan Brown rybrown at redhat.com
Thu Nov 13 15:39:58 UTC 2014

On 11/13/2014 09:58 AM, Clint Byrum wrote:
> Excerpts from Zane Bitter's message of 2014-11-13 05:54:03 -0800:
>> On 13/11/14 03:29, Murugan, Visnusaran wrote:

> [snip]

>>> 3.Migrate heat to use TaskFlow. (Too many code change)
>> If it's just handling timed triggers (maybe this is closer to #2) and 
>> not migrating the whole code base, then I don't see why it would be a 
>> big change (or even a change at all - it's basically new functionality). 
>> I'm not sure if TaskFlow has something like this already. If not we 
>> could also look at what Mistral is doing with timed tasks and see if we 
>> could spin some of it out into an Oslo library.
> I feel like it boils down to something running periodically checking for
> scheduled tasks that are due to run but have not run yet. I wonder if we
> can actually look at Ironic for how they do this, because Ironic polls
> power state of machines constantly, and uses a hash ring to make sure
> only one conductor is polling any one machine at a time. If we broke
> stacks up into a hash ring like that for the purpose of singleton tasks
> like timeout checking, that might work out nicely.


Using a hash ring is a great way to shard tasks. I think the most
sensible way to add this would be to make timeout polling a
responsibility of the Observer instead of the engine.

Ryan Brown / Software Engineer, Openstack / Red Hat, Inc.

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