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From "Hudson (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (HIVE-4423) Improve RCFile::sync(long) 10x
Date Sat, 27 Apr 2013 19:50:16 GMT

    [ https://issues.apache.org/jira/browse/HIVE-4423?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13643774#comment-13643774
] 

Hudson commented on HIVE-4423:
------------------------------

Integrated in Hive-trunk-h0.21 #2082 (See [https://builds.apache.org/job/Hive-trunk-h0.21/2082/])
    HIVE-4423 : Improve RCFile::sync(long) 10x (Gopal V via Ashutosh Chauhan) (Revision 1476648)

     Result = FAILURE
hashutosh : http://svn.apache.org/viewcvs.cgi/?root=Apache-SVN&view=rev&rev=1476648
Files : 
* /hive/trunk/ql/src/java/org/apache/hadoop/hive/ql/io/RCFile.java

                
> Improve RCFile::sync(long) 10x
> ------------------------------
>
>                 Key: HIVE-4423
>                 URL: https://issues.apache.org/jira/browse/HIVE-4423
>             Project: Hive
>          Issue Type: Improvement
>         Environment: Ubuntu LXC (1 SSD, 1 disk, 32 gigs of RAM)
>            Reporter: Gopal V
>            Assignee: Gopal V
>            Priority: Minor
>              Labels: optimization
>             Fix For: 0.12.0
>
>         Attachments: HIVE-4423.patch
>
>
> RCFile::sync(long) takes approx ~1 second everytime it gets called because of the inner
loops in the function.
> From what was observed with HDFS-4710, single byte reads are an order of magnitude slower
than larger 512 byte buffer reads. 
> Even when disk I/O is buffered to this size, there is overhead due to the synchronized
read() methods in BlockReaderLocal & RemoteBlockReader classes.
> Removing the readByte() calls in RCFile.sync(long) with a readFully(512 byte) call will
speed this function >10x.

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