Elliott Clark created HBASE-8517:
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Summary: Stochastic Loadbalancer isn't find steady state on real
clusters
Key: HBASE-8517
URL: https://issues.apache.org/jira/browse/HBASE-8517
Project: HBase
Issue Type: Bug
Reporter: Elliott Clark
Assignee: Elliott Clark
I have a cluster that runs IT tests. Last night after all tests were done I
noticed that the balancer was thrashing regions around.
The number of regions on each machine is not correct.
The balancer seems to value the cost of moving a region way too little.
{code}
2013-05-09 16:34:58,920 DEBUG [IPC Server handler 4 on 60000]
org.apache.hadoop.hbase.master.balancer.StochasticLoadBalancer: Finished
computing new load balance plan. Computation took 5367ms to try 8910 different
iterations. Found a solution that moves 37 regions; Going from a computed cost
of 56.50254222730425 to a new cost of 11.214035466575254
2013-05-09 16:37:48,715 DEBUG [IPC Server handler 7 on 60000]
org.apache.hadoop.hbase.master.balancer.StochasticLoadBalancer: Finished
computing new load balance plan. Computation took 4735ms to try 8910 different
iterations. Found a solution that moves 38 regions; Going from a computed cost
of 56.612624531830996 to a new cost of 11.275763861636982
2013-05-09 16:38:11,398 DEBUG [IPC Server handler 6 on 60000]
org.apache.hadoop.hbase.master.balancer.StochasticLoadBalancer: Finished
computing new load balance plan. Computation took 4502ms to try 8910 different
iterations. Found a solution that moves 39 regions; Going from a computed cost
of 56.50048461413552 to a new cost of 11.225352339003237
{code}
Each of those balancer runs were triggered when there was no load on the
cluster.
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