Hi Dev, Thanks for your response Imesh, if its ok, I’d like to skip straight to my (rather lengthy) question:
Does the autoscaler have, currently or plans to introduce, a means to receive an asynchronous event, signalling that a cartridge has gone from ‘SPAWNED’ to ‘ACTIVE’, after it is launched from a 'scale-up’ decision, so that, scaling decision interval can decrease to approximately the metric update interval, and multiple cartridges are not spawned when only one is needed? In more depth: The reasons for my question being that by knowing a cartridge is in the ‘SPAWNED’ or ’TERMINATING’ state, the aggregated metric averages can be ’transition compensated’ I.e… transistion-compensated-agg-ave = agg-ave * ( cluster-size / cluster-size + cluster-spawned-size - cluster–terminating-size ) To allow the scaling decisions to occur on a continuous (only throttled by the metric update frequency) basis. It appears that currently scaling decision occurs ~minutes. If this becomes ~seconds, it would vastly improving the maximum rate of ascent a cluster can scale against sudden increase in load. It appears that there is no spawning state awareness, which also means several ‘redundant’ instances get spawned, when instance startup time is greater than the scale decision interval. Finally: Are there difficulties in tracking ‘SPAWNED’ to ‘ACTIVE’ state on a per cartridge basis, how does this align (if its a valid enhancement) with other potential improvements that could be made to the autoscaler? Regards, Mike From: Imesh Gunaratne <[email protected]<mailto:[email protected]>> Reply-To: "[email protected]<mailto:[email protected]>" <[email protected]<mailto:[email protected]>> Date: Thursday, 12 February 2015 18:16 To: dev <[email protected]<mailto:[email protected]>> Subject: Re: autoscale architecture Hi Michael, Yes you can ask any questions you have on Autoscaling here. I don't think we have documented Autoscaling feature in 4.1.0 at the moment. However you could find some information here [1]. Autoscaling has slightly changed with Composite Application Model. [1] https://cwiki.apache.org/confluence/display/STRATOS/4.1.0+Autoscaler Thanks On Thu, Feb 12, 2015 at 9:33 PM, Michael Hall (michaha2) <[email protected]<mailto:[email protected]>> wrote: Hi Devs, Is there a resource or contact that can help me understand the current, and planned architecture of the autoscaling feature within Stratos. Best Regards, Mike -- Imesh Gunaratne Technical Lead, WSO2 Committer & PMC Member, Apache Stratos
