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 */
018
019package org.apache.hadoop.hbase.chaos.actions;
020
021import java.util.ArrayList;
022import java.util.LinkedList;
023import java.util.List;
024import org.apache.commons.lang3.RandomUtils;
025import org.apache.hadoop.hbase.ClusterMetrics;
026import org.apache.hadoop.hbase.ServerName;
027
028/**
029* Action that tries to unbalance the regions of a cluster.
030*/
031public class UnbalanceRegionsAction extends Action {
032  private double fractionOfRegions;
033  private double fractionOfServers;
034
035  /**
036   * Unbalances the regions on the cluster by choosing "target" servers, and moving
037   * some regions from each of the non-target servers to random target servers.
038   * @param fractionOfRegions Fraction of regions to move from each server.
039   * @param fractionOfServers Fraction of servers to be chosen as targets.
040   */
041  public UnbalanceRegionsAction(double fractionOfRegions, double fractionOfServers) {
042    this.fractionOfRegions = fractionOfRegions;
043    this.fractionOfServers = fractionOfServers;
044  }
045
046  @Override
047  public void perform() throws Exception {
048    LOG.info("Unbalancing regions");
049    ClusterMetrics status = this.cluster.getClusterMetrics();
050    List<ServerName> victimServers = new LinkedList<>(status.getLiveServerMetrics().keySet());
051    int targetServerCount = (int)Math.ceil(fractionOfServers * victimServers.size());
052    List<ServerName> targetServers = new ArrayList<>(targetServerCount);
053    for (int i = 0; i < targetServerCount; ++i) {
054      int victimIx = RandomUtils.nextInt(0, victimServers.size());
055      targetServers.add(victimServers.remove(victimIx));
056    }
057    unbalanceRegions(status, victimServers, targetServers, fractionOfRegions);
058  }
059}