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https://issues.apache.org/jira/browse/HBASE-3609?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13018728#comment-13018728
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Ted Yu commented on HBASE-3609:
-------------------------------
More background for Stan's cluster:
There're at least 600 regions on each region server. When 30 new regions were
created on the same region server, random selector only chose 3 out of the 30
new regions for reassignment. The other region selection was from inactive
(old) regions. This is expected behavior because new and old regions were
selected equally probably.
Basically we traded some optimization for safety of not overloading a newly
discovered region server.
My latest patch avoids the above behavior. At the same time, it also can deal
with a region server which just joined the cluster and should be assigned both
old and new regions.
> Improve the selection of regions to balance; part 2
> ---------------------------------------------------
>
> Key: HBASE-3609
> URL: https://issues.apache.org/jira/browse/HBASE-3609
> Project: HBase
> Issue Type: Improvement
> Reporter: stack
> Assignee: Ted Yu
> Attachments: 3609-alternate.txt, 3609-empty-RS.txt,
> hbase-3609-by-region-age.txt, hbase-3609.txt
>
>
> See 'HBASE-3586 Improve the selection of regions to balance' for discussion
> of algorithms that improve on current random assignment.
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