A question;

How is using something like celery in heat vs taskflow in heat (or at least 
concept [1]) 'to many code change'.

Both seem like change of similar levels ;-)

What was your metric for determining the code change either would have (out of 

Perhaps u should look at [2], although I'm unclear on what the desired 
functionality is here.

Do u want the single engine to transfer its work to another engine when it 
'goes down'? If so then the jobboard model + zookeper inherently does this.

Or maybe u want something else? I'm probably confused because u seem to be 
asking for resource timeouts + recover from engine failure (which seems like a 
liveness issue and not a resource timeout one), those 2 things seem separable.

[1] http://docs.openstack.org/developer/taskflow/jobs.html


On Nov 13, 2014, at 12:29 AM, Murugan, Visnusaran <visnusaran.muru...@hp.com> 

> Hi all,
> Convergence-POC distributes stack operations by sending resource actions over 
> RPC for any heat-engine to execute. Entire stack lifecycle will be controlled 
> by worker/observer notifications. This distributed model has its own 
> advantages and disadvantages.
> Any stack operation has a timeout and a single engine will be responsible for 
> it. If that engine goes down, timeout is lost along with it. So a traditional 
> way is for other engines to recreate timeout from scratch. Also a missed 
> resource action notification will be detected only when stack operation 
> timeout happens.
> To overcome this, we will need the following capability:
> 1.       Resource timeout (can be used for retry)
> 2.       Recover from engine failure (loss of stack timeout, resource action 
> notification)
> Suggestion:
> 1.       Use task queue like celery to host timeouts for both stack and 
> resource.
> 2.       Poll database for engine failures and restart timers/ retrigger 
> resource retry (IMHO: This would be a traditional and weighs heavy)
> 3.       Migrate heat to use TaskFlow. (Too many code change)
> I am not suggesting we use Task Flow. Using celery will have very minimum 
> code change. (decorate appropriate functions)
> Your thoughts.
> -Vishnu
> IRC: ckmvishnu
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