[
https://issues.apache.org/jira/browse/HBASE-13376?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14560093#comment-14560093
]
Ted Yu commented on HBASE-13376:
--------------------------------
In getLowestLocalRegionOnServer():
{code}
810 for (int j = 0; j < regionsPerServer[serverIndex].length; j++) {
...
819 }
820 LOG.debug(" Lowest locality region index is " +
lowestLocalRegionIndex
821 + " and its region server contains " +
regionsPerServer[serverIndex].length
822 + " regions");
823 return regionsPerServer[serverIndex][lowestLocalRegionIndex];
{code}
If the server doesn't have any region, accessing lowestLocalRegionIndex at line
823 would produce exception.
Better guard against this situation.
> Improvements to Stochastic load balancer
> ----------------------------------------
>
> Key: HBASE-13376
> URL: https://issues.apache.org/jira/browse/HBASE-13376
> Project: HBase
> Issue Type: Improvement
> Components: Balancer
> Affects Versions: 1.0.0, 0.98.12
> Reporter: Vandana Ayyalasomayajula
> Assignee: Vandana Ayyalasomayajula
> Priority: Minor
> Attachments: HBASE-13376_0.98.txt, HBASE-13376_0.txt,
> HBASE-13376_1.txt, HBASE-13376_98.patch
>
>
> There are two things this jira tries to address:
> 1. The locality picker in the stochastic balancer does not pick regions with
> least locality as candidates for swap/move. So when any user configures
> locality cost in the configs, the balancer does not always seems to move
> regions with bad locality.
> 2. When a cluster has equal number of loaded regions, it always picks the
> first one. It should pick a random region on one of the equally loaded
> servers. This improves a chance of finding a good candidate, when load picker
> is invoked several times.
--
This message was sent by Atlassian JIRA
(v6.3.4#6332)
