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https://issues.apache.org/jira/browse/YARN-5685?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15530951#comment-15530951
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Daniel Templeton commented on YARN-5685:
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I think I finally get it. The net is that HA now requires either Curator or
embedded to be enabled. Letting the {{ZKRMStateStore}} handle the RM state
transitions is no longer an option and hasn't been for a while. There are only
three ways {{transitionToActive()}} gets called:
# {{EmbeddedElectorService.becomeActive()}} -- embedded failover
# {{LeaderElectorService.isLeader()}} -- curator failover
# {{AdminService.transitionToActive()}} -- CLI
The question is what to do about non-embedded failover. I don't think it's
worth making non-embedded failover work again. I think we're better off
declaring non-embedded failover to be dead and removing the option altogether.
Given that this has been broken for a while and no one has noticed, I'm going
to bump the priority down a bit.
> Non-embedded HA failover is broken
> ----------------------------------
>
> Key: YARN-5685
> URL: https://issues.apache.org/jira/browse/YARN-5685
> Project: Hadoop YARN
> Issue Type: Bug
> Components: resourcemanager
> Affects Versions: 2.9.0, 3.0.0-alpha1
> Reporter: Daniel Templeton
> Assignee: Daniel Templeton
> Priority: Critical
>
> YARN-4559 broke RM HA when embedded automatic failover is disabled. The
> {{ZKRMStateStore}} will now only start its monitoring thread when automatic
> failover not enabled (which is patently useless). I presume the intended
> change was to have the monitoring thread started when automatic failover is
> not *embedded*.
> If HA is enabled with automatic failover enabled and embedded failover
> disabled, all RMs all come up in standby state. To make one of them active,
> the {{--forcemanual}} flag must be used when manually triggering the state
> change. Should the active go down, the standby will not become active and
> must be manually transitioned with the {{--forcemanual}} flag.
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