[jira] Commented: (HBASE-2240) Balancer should not reassign (because of overloading) a region that was just opened

["stack (JIRA)" <ji...@apache.org>]

    [ https://issues.apache.org/jira/browse/HBASE-2240?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12905100#action_12905100 ] 

stack commented on HBASE-2240:
------------------------------

This issue can happen with the new balancer.  New balancer is better in that it looks at the cluster as a whole and generates a plan that includes specification of where regions should be rebalanced too -- an improvement over what was there previous where any regionserver could be passed the unloaded region -- but the new balancer does not keep a history of what rebalances its done recently.  It should.

> Balancer should not reassign (because of overloading) a region that was just opened
> -----------------------------------------------------------------------------------
>
>                 Key: HBASE-2240
>                 URL: https://issues.apache.org/jira/browse/HBASE-2240
>             Project: HBase
>          Issue Type: Bug
>            Reporter: stack
>
> I'm running a mapreduce job.  I see a region split and its daughters come on line and then 8 seconds later, master judges the regionserver overloaded and so closes the just-opened region.  This messes up clients.   They may have just picked up the new location for their row query and now its moved again and client has to go hunting anew. 
> We need to assign the vintage regions first.
> I'm going to change balancer slop.  Its not sloppy enough and balancing cuts in too early.

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