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From "Misha Dmitriev (JIRA)" <j...@apache.org>
Subject [jira] [Updated] (HIVE-16166) HS2 may still waste up to 15% of memory on duplicate strings
Date Fri, 10 Mar 2017 01:07:37 GMT

     [ https://issues.apache.org/jira/browse/HIVE-16166?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
]

Misha Dmitriev updated HIVE-16166:
----------------------------------
    Attachment: ch_2_excerpt.txt

Results of jxray analysis for duplicate strings, baseline code.

> HS2 may still waste up to 15% of memory on duplicate strings
> ------------------------------------------------------------
>
>                 Key: HIVE-16166
>                 URL: https://issues.apache.org/jira/browse/HIVE-16166
>             Project: Hive
>          Issue Type: Improvement
>            Reporter: Misha Dmitriev
>            Assignee: Misha Dmitriev
>         Attachments: ch_2_excerpt.txt
>
>
> A heap dump obtained from one of our users shows that 15% of memory is wasted on duplicate
strings, despite the recent optimizations that I made. The problematic strings just come from
different sources this time. See the excerpt from the jxray (www.jxray.com) analysis attached.
> Adding String.intern() calls in the appropriate places reduces the overhead of duplicate
strings with this workload to ~6%. The remaining duplicates come mostly from JDK internal
and MapReduce data structures, and thus are more difficult to fix.



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