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https://issues.apache.org/jira/browse/HBASE-15529?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15292537#comment-15292537
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Guanghao Zhang commented on HBASE-15529:
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We use it in our production cluster one week. A use case of our cluster is:
{code}
2016-05-20,00:49:17,765 INFO
org.apache.hadoop.hbase.master.balancer.StochasticLoadBalancer: start
StochasticLoadBalancer.balaner, initCost=22.90110461931783,
functionCost=RegionCountSkewCostFunction : (25.0, 0.0); MoveCostFunction :
(5.0, 0.0); LocalityCostFunction : (30.0, 0.6408324325039945);
TableSkewCostFunction : (30.0, 0.018651123682791523); ReadRequestCostFunction :
(5.0, 0.4076729529674278); WriteRequestCostFunction : (5.0,
0.21564663377542329); MemstoreSizeCostFunction : (0.0, 0.13922403222035973);
StoreFileCostFunction : (0.0, 0.12878739127954114);
{code}
RegionCountSkewCost is 0.0 which means all rs have the same number of regions.
The original needsBalance method will return false because all rs have the same
number regions. So the StochasticLoadBalancer will not run even the
LocalityCost is 0.64.
The hbase version of our cluster is 0.98, it didn't have the feature of region
replica.
> Override needBalance in StochasticLoadBalancer
> ----------------------------------------------
>
> Key: HBASE-15529
> URL: https://issues.apache.org/jira/browse/HBASE-15529
> Project: HBase
> Issue Type: Improvement
> Reporter: Guanghao Zhang
> Assignee: Guanghao Zhang
> Priority: Minor
> Attachments: HBASE-15529-v1.patch, HBASE-15529.patch
>
>
> StochasticLoadBalancer includes cost functions to compute the cost of region
> rount, r/w qps, table load, region locality, memstore size, and storefile
> size. Every cost function returns a number between 0 and 1 inclusive and the
> computed costs are scaled by their respective multipliers. The bigger
> multiplier means that the respective cost function have the bigger weight.
> But needBalance decide whether to balance only by region count and doesn't
> consider r/w qps, locality even you config these cost function with bigger
> multiplier. StochasticLoadBalancer should override needBalance and decide
> whether to balance by it's configs of cost functions.
> Add one new config hbase.master.balancer.stochastic.minCostNeedBalance,
> cluster need balance when (total cost / sum multiplier) > minCostNeedBalance.
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