[jira] [Assigned] (HBASE-25832) Performance improvements for StochasticLoadBalancer

["Duo Zhang (Jira)" <ji...@apache.org>]

     [ https://issues.apache.org/jira/browse/HBASE-25832?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]

Duo Zhang reassigned HBASE-25832:
---------------------------------

    Assignee: Duo Zhang

> Performance improvements for StochasticLoadBalancer
> ---------------------------------------------------
>
>                 Key: HBASE-25832
>                 URL: https://issues.apache.org/jira/browse/HBASE-25832
>             Project: HBase
>          Issue Type: Improvement
>          Components: Balancer, Performance
>            Reporter: Duo Zhang
>            Assignee: Duo Zhang
>            Priority: Major
>
> This is what I posted in the slack channel.
> {quote}
> When refactoring balancer related code for moving them out to hbase-balancer module,  I found that we will create a OffPeakHours instance in MoveCostFunction.cost every time. So I wrote a simple JMH test to test its performance.
> https://github.com/Apache9/hbase-jmh-test/blob/master/src/main/java/org/apache/hadoop/hbase/master/balancer/MoveCostFunctionBenchmark.java
> For the original version,  the result is
> Benchmark                                            Mode  Samples    Score  Score error  Units
> o.a.h.h.m.b.MoveCostFunctionBenchmark.computeCost    avgt       10  242.312        3.853  ns/op
> 12:06
> If I initialized OffPeakHours in constructor, then the result is
> Benchmark                                            Mode  Samples   Score  Score error  Units
> o.a.h.h.m.b.MoveCostFunctionBenchmark.computeCost    avgt       10  81.186        0.720  ns/op
> 12:06
> If I also eliminate the conf.getFloat in the cost method(by storing them to a field member in constructor, the result is
> Benchmark                                            Mode  Samples  Score  Score error  Units
> o.a.h.h.m.b.MoveCostFunctionBenchmark.computeCost    avgt       10  4.419        0.035  ns/op
> 12:08
> I think on a large cluster, the performance for balancer is a problem, so maybe we should try to avoid creating too many objects or calling conf.getXXX in the critical path? As we will call StochasticLoadBalancer.computeCost in every step when balancing cluster...
> {quote}
> For large clusters, the performance of StochasticLoadBalancer will be very important, so I think we need to treat this problem seriously and try to improve.



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