[jira] [Updated] (AMBARI-21593) RU: AMS stopped after RU [AMS distributed mode]

["Aravindan Vijayan (JIRA)" <ji...@apache.org>]

     [ https://issues.apache.org/jira/browse/AMBARI-21593?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]

Aravindan Vijayan updated AMBARI-21593:
---------------------------------------
    Summary: RU: AMS stopped after RU [AMS distributed mode]  (was: cp /tmp/ambari-metrics-timelineservice-2.5.1.0.0.jar /usr/lib/ambari-metrics-collector/ambari-metrics-timelineservice-2.5.2.0.191.jar)

> RU: AMS stopped after RU [AMS distributed mode]
> -----------------------------------------------
>
>                 Key: AMBARI-21593
>                 URL: https://issues.apache.org/jira/browse/AMBARI-21593
>             Project: Ambari
>          Issue Type: Bug
>          Components: ambari-metrics
>    Affects Versions: 2.5.2
>            Reporter: Aravindan Vijayan
>            Assignee: Aravindan Vijayan
>            Priority: Blocker
>             Fix For: 2.5.2
>
>
> PROBLEM
> When 2 metric collectors are started up simultaneously, both of them fail to start.
> BUG
> There exists a race condition in the Metric Collector HA controller initialization which was introduced through AMBARI-20179. When a helix controller instance finds that the /ambari-metrics-collector znode exists but a child node does not exists, it deletes the entire znode and recreates. If another controller instance also initializes simultaneously, a race condition can occur wherein each instance will end up cancelling the effort of the other. 
> FIX
> Do not delete and recreate the znode. Wait and retry for a few seconds to check if /ambari-metrics-collector was fully initailized. 



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