[jira] [Commented] (YARN-4376) Memory Timeline Store return incorrect results on fromId paging

["Jonathan Eagles (JIRA)" <ji...@apache.org>]

    [ https://issues.apache.org/jira/browse/YARN-4376?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15018856#comment-15018856 ] 

Jonathan Eagles commented on YARN-4376:
---------------------------------------

According the [PriorityQueue|http://docs.oracle.com/javase/7/docs/api/java/util/PriorityQueue.html] java doc.

{code}
The Iterator provided in method iterator() is not guaranteed to traverse the elements of the priority queue in any particular order. If you need ordered traversal, consider using Arrays.sort(pq.toArray()).
{code}

> Memory Timeline Store return incorrect results on fromId paging
> ---------------------------------------------------------------
>
>                 Key: YARN-4376
>                 URL: https://issues.apache.org/jira/browse/YARN-4376
>             Project: Hadoop YARN
>          Issue Type: Bug
>            Reporter: Jonathan Eagles
>            Assignee: Jonathan Eagles
>
> As pointed out correctly by [~jlowe]. 
> https://issues.apache.org/jira/browse/TEZ-2628?focusedCommentId=14715831&page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel#comment-14715831
> The MemoryTimelineStore cannot page correctly when using fromId. This is due switching between data structures that apparently have different natural sorting. In addition, the approach of creating a new data structure every time from scratch is costly. 



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