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https://issues.apache.org/jira/browse/HBASE-8119?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13605827#comment-13605827
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Enis Soztutar commented on HBASE-8119:
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bq. Per table load balancing runs the balancer once per table.
The issue turned out to be not in the per-table load balancing, which was
already defaulted to false. The issue is that for 500 regions, Load balancer
takes 15 min, which makes it unusable. In it's current form,
StochasticLoadBalancer can only work with clusters having ~20 nodes, and low
hundreds of regions.
bq. There's a lot of hashmap manipulation that should be optimized out if we
wanted to worry about perf.
If the balancer takes more than 15 min, there is a bug in HMaster.balance()
that it breaks prematurely from assigning the region plans from the balancer.
One more thing is that we do not do bulk assign to the regions generated by the
load balancer plan.
> Optimize StochasticLoadBalancer
> -------------------------------
>
> Key: HBASE-8119
> URL: https://issues.apache.org/jira/browse/HBASE-8119
> Project: HBase
> Issue Type: Bug
> Components: Region Assignment
> Affects Versions: 0.95.0
> Reporter: Enis Soztutar
> Fix For: 0.95.0
>
>
> On a 5 node trunk cluster, I ran into a weird problem with
> StochasticLoadBalancer:
> server1 Thu Mar 14 03:42:50 UTC 2013 0.0 33
> server2 Thu Mar 14 03:47:53 UTC 2013 0.0 34
> server3 Thu Mar 14 03:46:53 UTC 2013 465.0 42
> server4 Thu Mar 14 03:47:53 UTC 2013 11455.0 282
> server5 Thu Mar 14 03:47:53 UTC 2013 0.0 34
> Total:5 11920 425
> Notice that server4 has 282 regions, while the others have much less. Plus
> for one table with 260 regions has been super imbalanced:
> {code}
> Regions by Region Server
> Region Server Region Count
> http://server3:60030/ 10
> http://server4:60030/ 250
> {code}
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