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Posted to common-dev@hadoop.apache.org by "Hudson (JIRA)" <ji...@apache.org> on 2008/07/01 14:56:45 UTC

[jira] Commented: (HADOOP-3556) Substitute the synchronized code in MD5Hash to avoid lock contention. Use ThreadLocal instead.

    [ https://issues.apache.org/jira/browse/HADOOP-3556?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12609564#action_12609564 ] 

Hudson commented on HADOOP-3556:
--------------------------------

Integrated in Hadoop-trunk #535 (See [http://hudson.zones.apache.org/hudson/job/Hadoop-trunk/535/])

> 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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