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https://issues.apache.org/jira/browse/HDFS-8818?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15993855#comment-15993855
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Tsz Wo Nicholas Sze commented on HDFS-8818:
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Hi [~kihwal], let's have a more detailed discussion before reverting.
The patch here (a thread pool per datanode pair) is indeed an improvement for
the previous design (a global thread pool) since it limits the number of
threads assigned to a particular datanode pair. Previously, if the first
datanode pair has a lot of pending moves, all the threads will be used to
execute the moves for that pair so that it will be very slow since it cannot
utilize the entire network.
We also has tested the new code a lot and see significant performance
improvement.
Have you tested it with HDFS-11377?
> Allow Balancer to run faster
> ----------------------------
>
> Key: HDFS-8818
> URL: https://issues.apache.org/jira/browse/HDFS-8818
> Project: Hadoop HDFS
> Issue Type: Sub-task
> Components: balancer & mover
> Reporter: Tsz Wo Nicholas Sze
> Assignee: Kihwal Lee
> Fix For: 2.8.0, 2.7.4, 3.0.0-alpha1
>
> Attachments: h8818_20150723.patch, h8818_20150727.patch,
> HDFS-8818-branch-2.7.00.patch
>
>
> The original design of Balancer is intentionally to make it run slowly so
> that the balancing activities won't affect the normal cluster activities and
> the running jobs.
> There are new use case that cluster admin may choose to balance the cluster
> when the cluster load is low, or in a maintain window. So that we should
> have an option to allow Balancer to run faster.
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