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From "Owen O'Malley (JIRA)" <j...@apache.org>
Subject [jira] Updated: (HADOOP-3556) Substitute the synchronized code in MD5Hash to avoid lock contention. Use ThreadLocal instead.
Date Mon, 30 Jun 2008 17:53:45 GMT

     [ https://issues.apache.org/jira/browse/HADOOP-3556?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
]

Owen O'Malley updated HADOOP-3556:
----------------------------------

       Resolution: Fixed
    Fix Version/s: 0.19.0
     Hadoop Flags: [Reviewed]
           Status: Resolved  (was: Patch Available)

I just committed this. Thanks, Iván!

> Substitute the synchronized code in MD5Hash to avoid lock contention. Use ThreadLocal
instead.
> ----------------------------------------------------------------------------------------------
>
>                 Key: HADOOP-3556
>                 URL: https://issues.apache.org/jira/browse/HADOOP-3556
>             Project: Hadoop Core
>          Issue Type: Improvement
>          Components: io
>            Reporter: Iván de Prado
>            Assignee: Iván de Prado
>             Fix For: 0.19.0
>
>         Attachments: 3556.patch, MD5Hash-ThreadLocal.patch
>
>
> Currently the MD5Hash class uses a singleton instance of the MessageDigester. The access
to this instance is synchronized, so MD5Hash has performance problems when used from several
Threads. I propose to substitute the singleton instance by a TheadLocal instances cache. I
will provide a patch.

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