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From "Gopal V (JIRA)" <j...@apache.org>
Subject [jira] [Updated] (HIVE-7144) GC pressure during ORC StringDictionary writes
Date Mon, 07 Jul 2014 22:31:35 GMT

     [ https://issues.apache.org/jira/browse/HIVE-7144?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
]

Gopal V updated HIVE-7144:
--------------------------

       Resolution: Fixed
    Fix Version/s: 0.14.0
           Status: Resolved  (was: Patch Available)

Committed to trunk, thanks [~hagleitn]!

> GC pressure during ORC StringDictionary writes 
> -----------------------------------------------
>
>                 Key: HIVE-7144
>                 URL: https://issues.apache.org/jira/browse/HIVE-7144
>             Project: Hive
>          Issue Type: Bug
>          Components: File Formats
>    Affects Versions: 0.14.0
>         Environment: ORC Table ~ 12 string columns
>            Reporter: Gopal V
>            Assignee: Gopal V
>              Labels: ORC, Performance
>             Fix For: 0.14.0
>
>         Attachments: HIVE-7144.1.patch, HIVE-7144.2.patch, HIVE-7144.3.patch, orc-string-write.png
>
>
> When ORC string dictionary writes data out, it suffers from bad GC performance due to
a few allocations in-loop.
> !orc-string-write.png!
> The conversions are as follows
> StringTreeWriter::getStringValue() causes 2 conversions
> LazyString -> Text (LazyString::getWritableObject)
> Text -> String (LazyStringObjectInspector::getPrimitiveJavaObject)
> Then StringRedBlackTree::add() does one conversion
> String -> Text
> This causes some GC pressure with un-necessary String and byte[] array allocations.



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