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HBASE-18164 Fast locality computation in balancer - addendum handles NaN 

-Added new LocalityCostFunction and LocalityCandidateGenerator that
cache localities of every region/rack combination and mappings of every
region to its most local server and to its most local rack.

-Made LocalityCostFunction incremental so that it only computes locality
based on most recent region moves/swaps, rather than recomputing the
locality of every region in the cluster at every iteration of the
balancer

-Changed locality cost function to reflect the ratio of:
(Current locality) / (Best locality possible given current cluster)

Signed-off-by: tedyu <yuzhihong@gmail.com>
This commit is contained in:
Kahlil Oppenheimer 2017-06-06 15:53:43 -04:00 committed by tedyu
parent 44c9c1de99
commit b4c3fe9763
1 changed files with 4 additions and 3 deletions
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7
hbase-server/src/main/java/org/apache/hadoop/hbase/master/balancer/StochasticLoadBalancer.java
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@ -1286,8 +1286,9 @@ public class StochasticLoadBalancer extends BaseLoadBalancer {
} }
// We normalize locality to be a score between 0 and 1.0 representing how good it // We normalize locality to be a score between 0 and 1.0 representing how good it
// is compared to how good it could be // is compared to how good it could be. If bestLocality is 0, assume locality is 100
locality /= bestLocality; // (and the cost is 0)
locality = bestLocality == 0 ? 1 : locality / bestLocality;
} }
@Override @Override
@ -1298,7 +1299,7 @@ public class StochasticLoadBalancer extends BaseLoadBalancer {
return; return;
} }
double localityDelta = getWeightedLocality(region, newEntity) - getWeightedLocality(region, oldEntity); double localityDelta = getWeightedLocality(region, newEntity) - getWeightedLocality(region, oldEntity);
double normalizedDelta = localityDelta / bestLocality; double normalizedDelta = bestLocality == 0 ? 0.0 : localityDelta / bestLocality;
locality += normalizedDelta; locality += normalizedDelta;
} }