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https://issues.apache.org/jira/browse/YARN-4692?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15152735#comment-15152735
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Arun Suresh commented on YARN-4692:
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[~leftnoteasy], Am not entirely convinced that Priorities will handle every
case.
Currently, a priority dictates the order in which the scheduler serves
allocations to a AMs resource request. Assuming a service is composed of
containers of 3 types (Slider i think currently calls them *roles* and each are
mapped to a yarn priority).
Taking the example of HBase, with Roles = Zookeeper, HBaseMaster and
HBaseRegionServer in decreasing priority order. This ensures that zookeeper
containers are started first.. and HBaseRS are started last. This establishes a
dependency order between Roles. Now I would argue that the *Preemptability*
cost of an HBaseRS container is higher than ZK, since, ZK can still function
without any problems if 1 or 2 container goes down (depending on the size of
the quorum) but if an RS goes down, it might take a while for the regions
hosted by the RS to be available again.
> [Umbrella] Simplified and first-class support for services in YARN
> ------------------------------------------------------------------
>
> Key: YARN-4692
> URL: https://issues.apache.org/jira/browse/YARN-4692
> Project: Hadoop YARN
> Issue Type: New Feature
> Reporter: Vinod Kumar Vavilapalli
> Assignee: Vinod Kumar Vavilapalli
> Attachments:
> YARN-First-Class-And-Simplified-Support-For-Services-v0.pdf
>
>
> YARN-896 focused on getting the ball rolling on the support for services
> (long running applications) on YARN.
> I’d like propose the next stage of this effort: _Simplified and first-class
> support for services in YARN_.
> The chief rationale for filing a separate new JIRA is threefold:
> - Do a fresh survey of all the things that are already implemented in the
> project
> - Weave a comprehensive story around what we further need and attempt to
> rally the community around a concrete end-goal, and
> - Additionally focus on functionality that YARN-896 and friends left for
> higher layers to take care of and see how much of that is better integrated
> into the YARN platform itself.
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