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From Iván de Prado (JIRA) <j...@apache.org>
Subject [jira] Commented: (HADOOP-3556) Substitute the synchronized code in MD5Hash to avoid lock contention. Use ThreadLocal instead.
Date Mon, 16 Jun 2008 13:57:45 GMT

    [ https://issues.apache.org/jira/browse/HADOOP-3556?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12605291#action_12605291
] 

Iván de Prado commented on HADOOP-3556:
---------------------------------------

I have changed the status to "Resume Progress", then I attached a new patch with some more
unit tests, but I can not find the link for changing to status "Submit Patch". Could you help
me with that?

> 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
>            Reporter: Iván de Prado
>         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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