hbase-issues mailing list archives

Site index · List index
Message view « Date » · « Thread »
Top « Date » · « Thread »
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 Thu, 04 Dec 2014 02:31:12 GMT

    [ https://issues.apache.org/jira/browse/HBASE-12431?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14233839#comment-14233839
] 

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

Thanks for the comments [~stack] and [~enis].
The variable of ThreadLocal is a static one and just instantiated only once. The instantiation
of ThreadLocal does nothing, only when there's value added, the map inside the ThreadLocal
is initialized.
This means the current patch is a lazy implementation.
# Instantiate the ThreadLocal as a static one.
# Add the buffer into the ThreadLocal lazily only when a thread uses it.
Please advise. Thanks.

> 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: 1.0.0, 2.0.0, 0.98.9
>
>         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.



--
This message was sent by Atlassian JIRA
(v6.3.4#6332)

Mime
View raw message