View Javadoc

1   /**
2    * Licensed to the Apache Software Foundation (ASF) under one
3    * or more contributor license agreements.  See the NOTICE file
4    * distributed with this work for additional information
5    * regarding copyright ownership.  The ASF licenses this file
6    * to you under the Apache License, Version 2.0 (the
7    * "License"); you may not use this file except in compliance
8    * with the License.  You may obtain a copy of the License at
9    *
10   *     http://www.apache.org/licenses/LICENSE-2.0
11   *
12   * Unless required by applicable law or agreed to in writing, software
13   * distributed under the License is distributed on an "AS IS" BASIS,
14   * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
15   * See the License for the specific language governing permissions and
16   * limitations under the License.
17   */
18  
19  package org.apache.hadoop.hbase.chaos.actions;
20  
21  import java.util.ArrayList;
22  import java.util.LinkedList;
23  import java.util.List;
24  
25  import org.apache.commons.lang.math.RandomUtils;
26  import org.apache.hadoop.hbase.ClusterStatus;
27  import org.apache.hadoop.hbase.ServerName;
28  
29  /**
30  * Action that tries to unbalance the regions of a cluster.
31  */
32  public class UnbalanceRegionsAction extends Action {
33    private double fractionOfRegions;
34    private double fractionOfServers;
35  
36    /**
37     * Unbalances the regions on the cluster by choosing "target" servers, and moving
38     * some regions from each of the non-target servers to random target servers.
39     * @param fractionOfRegions Fraction of regions to move from each server.
40     * @param fractionOfServers Fraction of servers to be chosen as targets.
41     */
42    public UnbalanceRegionsAction(double fractionOfRegions, double fractionOfServers) {
43      this.fractionOfRegions = fractionOfRegions;
44      this.fractionOfServers = fractionOfServers;
45    }
46  
47    @Override
48    public void perform() throws Exception {
49      LOG.info("Unbalancing regions");
50      ClusterStatus status = this.cluster.getClusterStatus();
51      List<ServerName> victimServers = new LinkedList<ServerName>(status.getServers());
52      int targetServerCount = (int)Math.ceil(fractionOfServers * victimServers.size());
53      List<ServerName> targetServers = new ArrayList<ServerName>(targetServerCount);
54      for (int i = 0; i < targetServerCount; ++i) {
55        int victimIx = RandomUtils.nextInt(victimServers.size());
56        targetServers.add(victimServers.remove(victimIx));
57      }
58      unbalanceRegions(status, victimServers, targetServers, fractionOfRegions);
59    }
60  }