[jira] [Created] (HBASE-24138) Ensure StochasticLoadBalancer can log details of decision to not run balancer

["Sean Busbey (Jira)" <ji...@apache.org>]

Sean Busbey created HBASE-24138:
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             Summary: Ensure StochasticLoadBalancer can log details of decision to not run balancer
                 Key: HBASE-24138
                 URL: https://issues.apache.org/jira/browse/HBASE-24138
             Project: HBase
          Issue Type: Task
          Components: Balancer, Operability
            Reporter: Sean Busbey
            Assignee: Sean Busbey


Ran into a customer case where the StochasticLoadBalancer was consistently deciding not to balance when bringing new region servers on line. Even setting the class to TRACE logging would only log a summary statement like:

{code}
2020-04-03 00:29:55,133 TRACE org.apache.hadoop.hbase.master.balancer.StochasticLoadBalancer: Skipping load balancing because balanced cluster; total cost is 25.24853189705185, sum multiplier is 602.0 min cost which need balance is 0.05
{code}

Without any details about what went into that decision it's really hard to figure out if what we need to tune to get the behavior we want.



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