[jira] [Commented] (YARN-5169) most YARN events have timestamp of -1

["Sangjin Lee (JIRA)" <ji...@apache.org>]

    [ https://issues.apache.org/jira/browse/YARN-5169?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15304349#comment-15304349 ] 

Sangjin Lee commented on YARN-5169:
-----------------------------------

I'd also point out there is already some code in the timeline service (e.g. {{SystemMetricsPublisher}}) that "fills in this timestamp" with the current timestamp for some events when writing to storage. However, strictly speaking this is the time when the data is written to the timeline service storage, and is not necessarily the same thing as the actual event timestamp.

> 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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