[jira] [Commented] (ACCUMULO-3079) improve system iterator performance by collapsing call stack

["Josh Elser (JIRA)" <ji...@apache.org>]

    [ https://issues.apache.org/jira/browse/ACCUMULO-3079?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14107132#comment-14107132 ] 

Josh Elser commented on ACCUMULO-3079:
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Nifty, did you use the code from ACCUMULO-3067 to see the performance improvements? Anything else that can be replicated?

> improve system iterator performance by collapsing call stack
> ------------------------------------------------------------
>
>                 Key: ACCUMULO-3079
>                 URL: https://issues.apache.org/jira/browse/ACCUMULO-3079
>             Project: Accumulo
>          Issue Type: Improvement
>            Reporter: Adam Fuchs
>            Assignee: Adam Fuchs
>             Fix For: 1.6.1, 1.7.0
>
>         Attachments: iterator_performance_20140822_1.patch
>
>
> System iterators are at the core of the tightest loops in Accumulo, handling every key/value pair that traverses through a scan or a compaction. In many cases, iterators are the current performance bottleneck for Accumulo. Every bit that we can improve performance in the iterators translates into better performance for Accumulo.
> There are several strategies that can be applied to the current code base to improve performance, including:
>  # Inlining calls that are hard for the JVM to inline at runtime
>  # Moving checks for null outside of tight loops when they are invariants within the loop
>  # Eliminating "no-op" iterators at iterator tree construction time
>  # Making frequently used and assigned-once objects final (like iterator sources)



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