Duo Zhang created HBASE-25832:
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Summary: 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
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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