001/* 002 * Licensed to the Apache Software Foundation (ASF) under one 003 * or more contributor license agreements. See the NOTICE file 004 * distributed with this work for additional information 005 * regarding copyright ownership. The ASF licenses this file 006 * to you under the Apache License, Version 2.0 (the 007 * "License"); you may not use this file except in compliance 008 * with the License. You may obtain a copy of the License at 009 * 010 * http://www.apache.org/licenses/LICENSE-2.0 011 * 012 * Unless required by applicable law or agreed to in writing, software 013 * distributed under the License is distributed on an "AS IS" BASIS, 014 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 015 * See the License for the specific language governing permissions and 016 * limitations under the License. 017 */ 018package org.apache.hadoop.hbase.master.balancer; 019 020import org.apache.hadoop.conf.Configuration; 021import org.apache.yetus.audience.InterfaceAudience; 022 023/** 024 * Compute the cost of a potential cluster state from skew in number of regions on a cluster. 025 */ 026@InterfaceAudience.Private 027class RegionCountSkewCostFunction extends CostFunction { 028 029 static final String REGION_COUNT_SKEW_COST_KEY = 030 "hbase.master.balancer.stochastic.regionCountCost"; 031 static final float DEFAULT_REGION_COUNT_SKEW_COST = 500; 032 033 private final DoubleArrayCost cost = new DoubleArrayCost(); 034 035 RegionCountSkewCostFunction(Configuration conf) { 036 // Load multiplier should be the greatest as it is the most general way to balance data. 037 this.setMultiplier(conf.getFloat(REGION_COUNT_SKEW_COST_KEY, DEFAULT_REGION_COUNT_SKEW_COST)); 038 } 039 040 @Override 041 void prepare(BalancerClusterState cluster) { 042 super.prepare(cluster); 043 cost.prepare(cluster.numServers); 044 cost.applyCostsChange(costs -> { 045 for (int i = 0; i < cluster.numServers; i++) { 046 costs[i] = cluster.regionsPerServer[i].length; 047 } 048 }); 049 } 050 051 @Override 052 protected double cost() { 053 return cost.cost(); 054 } 055 056 @Override 057 protected void regionMoved(int region, int oldServer, int newServer) { 058 cost.applyCostsChange(costs -> { 059 costs[oldServer] = cluster.regionsPerServer[oldServer].length; 060 costs[newServer] = cluster.regionsPerServer[newServer].length; 061 }); 062 } 063 064 @Override 065 public final void updateWeight(double[] weights) { 066 weights[StochasticLoadBalancer.GeneratorType.LOAD.ordinal()] += cost(); 067 } 068}