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From "Tsz Wo (Nicholas), SZE (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (HDFS-4992) Make balancer's thread count configurable
Date Tue, 16 Jul 2013 03:24:49 GMT

    [ https://issues.apache.org/jira/browse/HDFS-4992?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13709415#comment-13709415

Tsz Wo (Nicholas), SZE commented on HDFS-4992:

Hi Max, thanks for submitting a patch.  Some minor comments:

- Could you add the new conf properties and the default values to DFSConfigKeys?  You may

- Let's keep moverExecutor and dispatcherExecutor as final.

Patch looks good other than that.
> Make balancer's thread count configurable
> -----------------------------------------
>                 Key: HDFS-4992
>                 URL: https://issues.apache.org/jira/browse/HDFS-4992
>             Project: Hadoop HDFS
>          Issue Type: Improvement
>          Components: balancer
>            Reporter: Max Lapan
>         Attachments: HDFS-4992-v1.patch
> By default, balancer has 1000 threads which moves blocks around (mover threads) and 200
threads which decide which block to move (dispatcher threads).
> On large clusters, 1000 threads creates significant load on NN, which slows down other
HDFS activity. For example, on our cluster, 'hdfs dfs -ls /' command took about 1 minute when
balancer is active. When no balancing in progress, the same command finishes in second or
> This patch makes amount of threads configurable by two new options 'dfs.balancer.moverThreads'
and 'dfs.balancer.dispatcherThreads'.

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