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From "Li Lu (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (YARN-5169) most YARN events have timestamp of -1
Date Fri, 27 May 2016 18:52:13 GMT

    [ https://issues.apache.org/jira/browse/YARN-5169?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15304555#comment-15304555
] 

Li Lu commented on YARN-5169:
-----------------------------

Thanks [~sjlee0] for raising this issue! I noticed that in RM's SystemMetricsPublisher code,
we're creating {{SystemMetricEvent}}s which will always have timestamps. Those timestamps
are typically generated by the call-sites of each system metrics publisher call. For example,
in {{appACLsUpdated}} call, the update time is generated in RMAppManager#createAndPopulateNewRMApp.
Similarly, appFinished method of SMP is called in RMAppImpl, when we perform the final state
transition to final state. We also generate the finish time at that time. Maybe we'd like
to provide a similar mechanism in the NM? That is to say, we can have NMMetricsEvent exposed
in NM's source code, and create those events when we publish the data (instead of using timestamps
of existing events)? I think we may put part of this work in trunk, but one concern is the
newly introduced NMMetricsEvent will not be used in trunk but just in YARN-2928 branch...


> most YARN events have timestamp of -1
> -------------------------------------
>
>                 Key: YARN-5169
>                 URL: https://issues.apache.org/jira/browse/YARN-5169
>             Project: Hadoop YARN
>          Issue Type: Bug
>          Components: yarn
>    Affects Versions: 2.7.2
>            Reporter: Sangjin Lee
>
> Most of the YARN events (subclasses of {{AbstractEvent}}) have timestamp of -1. {{AbstractEvent}}
have two constructors, one that initializes the timestamp to -1 and the other to the caller-provided
value. But most events use the former (thus timestamp of -1).
> Some of the more common events, including {{ApplicationEvent}}, {{ContainerEvent}}, {{JobEvent}},
etc. do not set the timestamp.
> The rationale for this behavior seems to be mentioned in {{AbstractEvent}}:
> {code}
>   // use this if you DON'T care about the timestamp
>   public AbstractEvent(TYPE type) {
>     this.type = type;
>     // We're not generating a real timestamp here.  It's too expensive.
>     timestamp = -1L;
>   }
> {code}
> This absence of the timestamp isn't really visible in many cases and therefore may have
gone unnoticed, but the timeline service exposes this problem very visibly.



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