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From "Jingcheng Du (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (HBASE-12431) Use of getColumnLatestCell(byte[], int, int, byte[], int, int) is Not Thread Safe
Date Fri, 07 Nov 2014 05:24:34 GMT

    [ https://issues.apache.org/jira/browse/HBASE-12431?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14201615#comment-14201615
] 

Jingcheng Du commented on HBASE-12431:
--------------------------------------

The test results are listed following.
Before applying the patch
loadValue(): 260087188618
getValue():  280990331150

After applying the patch
loadValue(): 262340481358
getValue():  281435842873

In loadValue(), it shows 0.87% performance degrade.
In getValue(), it shows 0.16% performance degrade.


> Use of getColumnLatestCell(byte[], int, int, byte[], int, int) is Not Thread Safe
> ---------------------------------------------------------------------------------
>
>                 Key: HBASE-12431
>                 URL: https://issues.apache.org/jira/browse/HBASE-12431
>             Project: HBase
>          Issue Type: Bug
>          Components: Client
>    Affects Versions: 0.98.1
>            Reporter: Jonathan Jarvis
>            Assignee: Jingcheng Du
>             Fix For: 2.0.0, 0.98.8, 0.99.2
>
>         Attachments: HBASE-12431-V2.diff, HBASE-12431-V3.diff, HBASE-12431.diff
>
>
> Result declares that it is NOT THREAD SAFE at the top of the source code, but one would
assume that refers to many different threads accessing the same Result object. I've run into
an issue when I have several different threads accessing their own Result object that runs
into an issue because of use of common static member variable.
> I noticed the problem when I switched from:
> getColumnLatestCell(byte[], byte[]) to
> getColumnLatestCell(byte[], int, int, byte[], int, int)
> These methods call different binarySearch methods, the latter invoking:
> protected int  binarySearch(final Cell [] kvs,
> 309      final byte [] family, final int foffset, final int flength,
> 310      final byte [] qualifier, final int qoffset, final int qlength) {
> This method utilizes a private static member variable called "buffer"
> If more than one thread is utilizing "buffer" you'll see unpredictable behavior unless
you synchronize(Result.class) {}.
> If buffer is to remain a static variable, I would recommend changing it to a ThreadLocal<byte[]>
instead.



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