1   /**
2    * Copyright 2007 The Apache Software Foundation
3    *
4    * Licensed to the Apache Software Foundation (ASF) under one
5    * or more contributor license agreements.  See the NOTICE file
6    * distributed with this work for additional information
7    * regarding copyright ownership.  The ASF licenses this file
8    * to you under the Apache License, Version 2.0 (the
9    * "License"); you may not use this file except in compliance
10   * with the License.  You may obtain a copy of the License at
11   *
12   *     http://www.apache.org/licenses/LICENSE-2.0
13   *
14   * Unless required by applicable law or agreed to in writing, software
15   * distributed under the License is distributed on an "AS IS" BASIS,
16   * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
17   * See the License for the specific language governing permissions and
18   * limitations under the License.
19   */
20  package org.apache.hadoop.hbase.master;
21  
22  import java.io.IOException;
23  import java.util.ArrayList;
24  import java.util.List;
25  
26  import org.apache.hadoop.hbase.HBaseConfiguration;
27  import org.apache.hadoop.hbase.HMsg;
28  import org.apache.hadoop.hbase.HRegionInfo;
29  import org.apache.hadoop.hbase.HServerInfo;
30  import org.apache.zookeeper.KeeperException;
31  
32  /**
33   * An HMaster that runs out of memory.
34   * Everytime a region server reports in, add to the retained heap of memory.
35   * Needs to be started manually as in
36   * <code>${HBASE_HOME}/bin/hbase ./bin/hbase org.apache.hadoop.hbase.OOMEHMaster start/code>.
37   */
38  public class OOMEHMaster extends HMaster {
39    private List<byte []> retainer = new ArrayList<byte[]>();
40  
41    public OOMEHMaster(HBaseConfiguration conf)
42    throws IOException, KeeperException, InterruptedException {
43      super(conf);
44    }
45  
46    @Override
47    public HMsg[] regionServerReport(HServerInfo serverInfo, HMsg[] msgs,
48      HRegionInfo[] mostLoadedRegions)
49    throws IOException {
50      // Retain 1M.
51      this.retainer.add(new byte [1024 * 1024]);
52      return super.regionServerReport(serverInfo, msgs, mostLoadedRegions);
53    }
54  
55    public static void main(String[] args) throws Exception {
56      new HMasterCommandLine(OOMEHMaster.class).doMain(args);
57    }
58  }