[jira] Updated: (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:all-tabpanel ]

stack updated HBASE-2240:
-------------------------

       Priority: Minor  (was: Major)
    Component/s: documentation

bq. Is there some reason we would never want to rebalance a region that was just recently opened (for some definition of recent).

Yes. It takes clients a while finding new locations.  With our current client at least, reopens that come close together can result in the client failing with NSRE.

History would also help prevent the slightly pathological case where its always the same region that gets moved on a rebalance.

Currently balancer runs every minute.  I should up the default.

Marking issue minor.

> 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
>          Components: documentation
>            Reporter: stack
>            Priority: Minor
>
> 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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