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Date: Fri, 27 May 2016 21:36:13 +0000 (UTC)
From: "Li Lu (JIRA)" <jira@apache.org>
To: yarn-issues@hadoop.apache.org
Message-ID: <JIRA.12973290.1464321287000.321279.1464384973251@Atlassian.JIRA>
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References: <JIRA.12973290.1464321287000@Atlassian.JIRA> <JIRA.12973290.1464321287194@arcas>
Subject: [jira] [Commented] (YARN-5169) most YARN events have timestamp of
 -1
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archived-at: Fri, 27 May 2016 21:36:15 -0000


    [ https://issues.apache.org/jira/browse/YARN-5169?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15304844#comment-15304844 ] 

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

Thanks [~sjlee0]! 

bq.  Are event timestamps for consumption by the timeline service exclusively? Or should we expect them to have reasonable timestamps more generally?
Right now timeline service may be the only user of this data, but providing this information would certainly be helpful to other components. 

bq. And also is the rationale of not generating the timestamp by default (being too expensive) still a valid conclusion?
This is also my concern. For NMs, my hunch is we have much less events generated, therefore performance problem should be less severe? 

> 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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