server/balancer/TestBalancerWithNodeGroup.java

/**
 * Licensed to the Apache Software Foundation (ASF) under one
 * or more contributor license agreements.  See the NOTICE file
 * distributed with this work for additional information
 * regarding copyright ownership.  The ASF licenses this file
 * to you under the Apache License, Version 2.0 (the
 * "License"); you may not use this file except in compliance
 * with the License.  You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
package org.apache.hadoop.hdfs.server.balancer;

import static org.junit.Assert.assertEquals;

import java.io.IOException;
import java.util.HashMap;
import java.util.Map;
import java.util.Random;
import java.util.concurrent.TimeoutException;

import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;
import org.apache.hadoop.conf.Configuration;
import org.apache.hadoop.fs.FileSystem;
import org.apache.hadoop.fs.Path;
import org.apache.hadoop.hdfs.DFSClient;
import org.apache.hadoop.hdfs.DFSTestUtil;
import org.apache.hadoop.hdfs.MiniDFSClusterWithNodeGroup;
import org.apache.hadoop.hdfs.protocol.ClientProtocol;
import org.apache.hadoop.hdfs.protocol.DatanodeInfo;
import org.apache.hadoop.hdfs.protocol.FSConstants.DatanodeReportType;
import org.apache.hadoop.hdfs.server.datanode.SimulatedFSDataset;
import org.apache.hadoop.net.NetworkTopology;
import org.junit.Assert;
import org.junit.Test;

/**
 * This class tests if a balancer schedules tasks correctly.
 */
public class TestBalancerWithNodeGroup {

  final private static long CAPACITY = 500L;
  final private static String RACK0 = "/rack0";
  final private static String RACK1 = "/rack1";
  final private static String NODEGROUP0 = "/nodegroup0";
  final private static String NODEGROUP1 = "/nodegroup1";
  final private static String NODEGROUP2 = "/nodegroup2";
  final static private String fileName = "/tmp.txt";
  final static private Path filePath = new Path(fileName);
  private static final Log LOG = LogFactory.getLog(
      "org.apache.hadoop.hdfs.TestBalancerWithNodeGroup");
  MiniDFSClusterWithNodeGroup cluster;

  ClientProtocol client;
  private Balancer balancer;

  static final long TIMEOUT = 20000L; //msec
  static final double CAPACITY_ALLOWED_VARIANCE = 0.005;  // 0.5%
  static final double BALANCE_ALLOWED_VARIANCE = 0.11;    // 10%+delta
  static final int DEFAULT_BLOCK_SIZE = 5;
  private static final Random r = new Random();

  static {
    Balancer.setBlockMoveWaitTime(1000L) ;
  }

  private void initConf(Configuration conf) {
    conf.setLong("dfs.block.size", DEFAULT_BLOCK_SIZE);
    conf.setInt("io.bytes.per.checksum", DEFAULT_BLOCK_SIZE);
    conf.setLong("dfs.heartbeat.interval", 1L);
    conf.setBoolean(SimulatedFSDataset.CONFIG_PROPERTY_SIMULATED, true);
    conf.setLong("dfs.balancer.movedWinWidth", 2000L);
    conf.set("net.topology.impl", "org.apache.hadoop.net.NetworkTopologyWithNodeGroup");
    conf.set("dfs.block.replicator.classname",
        "org.apache.hadoop.hdfs.server.namenode.BlockPlacementPolicyWithNodeGroup");
  }

  /* create a file with a length of <code>fileLen</code> */
  private void createFile(long fileLen, short replicationFactor)
      throws IOException {
    FileSystem fs = cluster.getFileSystem();
    DFSTestUtil.createFile(fs, filePath, fileLen,
        replicationFactor, r.nextLong());
    DFSTestUtil.waitReplication(fs, filePath, replicationFactor);
  }

  // create and initiate conf for balancer
  private Configuration createConf() {
    Configuration conf = new Configuration();
    initConf(conf);
    return conf;
  }

  /**
   * Wait until heartbeat gives expected results, within CAPACITY_ALLOWED_VARIANCE,
   * summed over all nodes.  Times out after TIMEOUT msec.
   * @param expectedUsedSpace
   * @param expectedTotalSpace
   * @throws IOException - if getStats() fails
   * @throws TimeoutException
   */
  private void waitForHeartBeat(long expectedUsedSpace, long expectedTotalSpace)
  throws IOException, TimeoutException {
    long timeout = TIMEOUT;
    long failtime = (timeout <= 0L) ? Long.MAX_VALUE
             : System.currentTimeMillis() + timeout;

    while (true) {
      long[] status = client.getStats();
      double totalSpaceVariance = Math.abs((double)status[0] - expectedTotalSpace)
          / expectedTotalSpace;
      double usedSpaceVariance = Math.abs((double)status[1] - expectedUsedSpace)
          / expectedUsedSpace;
      if (totalSpaceVariance < CAPACITY_ALLOWED_VARIANCE
          && usedSpaceVariance < CAPACITY_ALLOWED_VARIANCE)
        break; //done

      if (System.currentTimeMillis() > failtime) {
        throw new TimeoutException("Cluster failed to reached expected values of "
            + "totalSpace (current: " + status[0]
            + ", expected: " + expectedTotalSpace
            + "), or usedSpace (current: " + status[1]
            + ", expected: " + expectedUsedSpace
            + "), in more than " + timeout + " msec.");
      }
      try {
        Thread.sleep(100L);
      } catch(InterruptedException ignored) {
      }
    }
  }

  /**
   * Wait until balanced: each datanode gives utilization within
   * BALANCE_ALLOWED_VARIANCE of average
   * @throws IOException
   * @throws TimeoutException
   */
  private void waitForBalancer(long totalUsedSpace, long totalCapacity)
      throws IOException, TimeoutException {
    long timeout = TIMEOUT;
    long failtime = (timeout <= 0L) ? Long.MAX_VALUE
        : System.currentTimeMillis() + timeout;
    final double avgUtilization = ((double)totalUsedSpace) / totalCapacity;
    boolean balanced;
    do {
      DatanodeInfo[] datanodeReport =
          client.getDatanodeReport(DatanodeReportType.ALL);
      assertEquals(datanodeReport.length, cluster.getDataNodes().size());
      balanced = true;
      for (DatanodeInfo datanode : datanodeReport) {
        double nodeUtilization = ((double)datanode.getDfsUsed())
            / datanode.getCapacity();
        if (Math.abs(avgUtilization - nodeUtilization) >
            BALANCE_ALLOWED_VARIANCE) {
          balanced = false;
          if (System.currentTimeMillis() > failtime) {
            throw new TimeoutException(
                "Rebalancing expected avg utilization to become "
                + avgUtilization + ", but on datanode " + datanode
                + " it remains at " + nodeUtilization
                + " after more than " + TIMEOUT + " msec.");
          }
          try {
            Thread.sleep(100);
          } catch (InterruptedException ignored) {
          }
          break;
        }
      }
    } while (!balanced);
  }

  /** Start balancer and check if the cluster is balanced after the run */
  private void runBalancer(Configuration conf,
      long totalUsedSpace, long totalCapacity) throws Exception {
    waitForHeartBeat(totalUsedSpace, totalCapacity);

    // start rebalancing
    balancer = new Balancer(conf);

    final int r = balancer.run(new String[0]);

    assertEquals(Balancer.SUCCESS, r);

    waitForHeartBeat(totalUsedSpace, totalCapacity);
    LOG.info("Rebalancing with default factor.");
    waitForBalancer(totalUsedSpace, totalCapacity);
  }

  private void runBalancerCanFinish(Configuration conf,
      long totalUsedSpace, long totalCapacity) throws Exception {
    waitForHeartBeat(totalUsedSpace, totalCapacity);

    balancer = new Balancer(conf);
    final int r = balancer.run(new String[0]);
    Assert.assertTrue(r == Balancer.SUCCESS ||
        (r == Balancer.NO_MOVE_PROGRESS));
    waitForHeartBeat(totalUsedSpace, totalCapacity);
    LOG.info("Rebalancing ends successful.");
  }

  /**
   * Create a 4 nodes cluster: 2 nodes (n0, n1) in RACK0/NODEGROUP0, 1 node (n2)
   * in RACK1/NODEGROUP1 and 1 node (n3) in RACK1/NODEGROUP2. Fill the cluster
   * to 60% and 3 replicas, so n2 and n3 will have replica for all blocks according
   * to replica placement policy with NodeGroup. As a result, n2 and n3 will be
   * filled with 80% (60% x 4 / 3), and no blocks can be migrated from n2 and n3
   * to n0 or n1 as balancer policy with node group. Thus, we expect the balancer
   * to end in 5 iterations without move block process.
   */
  @Test(timeout=60000)
  public void testBalancerEndInNoMoveProgress() throws Exception {
    Configuration conf = createConf();
    long[] capacities = new long[]{CAPACITY, CAPACITY, CAPACITY, CAPACITY};
    String[] racks = new String[]{RACK0, RACK0, RACK1, RACK1};
    String[] nodeGroups = new String[]{NODEGROUP0, NODEGROUP0, NODEGROUP1, NODEGROUP2};

    int numOfDatanodes = capacities.length;
    assertEquals(numOfDatanodes, racks.length);
    assertEquals(numOfDatanodes, nodeGroups.length);
    MiniDFSClusterWithNodeGroup.setNodeGroups(nodeGroups);
    cluster = new MiniDFSClusterWithNodeGroup(0, conf, capacities.length,
        true, true, null, racks, capacities);
    try {
      cluster.waitActive();
      client = DFSClient.createNamenode(conf);

      long totalCapacity = 0L;
      for(long capacity : capacities) {
        totalCapacity += capacity;
      }

      // fill up the cluster to be 60% full
      long totalUsedSpace = totalCapacity * 6 / 10;

      createFile(totalUsedSpace / 3, (short) 3);

      // run balancer which can finish in 5 iterations with no block movement.
      runBalancerCanFinish(conf, totalUsedSpace, totalCapacity);

    } finally {
      cluster.shutdown();
    }
  }

  /**
   * Create a cluster with even distribution, and a new empty node is added to
   * the cluster, then test rack locality for balancer policy.
   */
  @Test(timeout=60000)
  public void testBalancerWithRackLocality() throws Exception {
    Configuration conf = createConf();
    long[] capacities = new long[]{CAPACITY, CAPACITY};
    String[] racks = new String[]{RACK0, RACK1};
    String[] nodeGroups = new String[]{NODEGROUP0, NODEGROUP1};

    int numOfDatanodes = capacities.length;
    assertEquals(numOfDatanodes, racks.length);
    MiniDFSClusterWithNodeGroup.setNodeGroups(nodeGroups);

    MiniDFSClusterWithNodeGroup.setNodeGroups(nodeGroups);
    cluster = new MiniDFSClusterWithNodeGroup(0, conf, capacities.length,
        true, true, null, racks, capacities);
    try {
      cluster.waitActive();

      client = DFSClient.createNamenode(conf);

      long totalCapacity = 0L;
      for(long capacity : capacities) {
        totalCapacity += capacity;
      }

      // fill up the cluster to be 30% full
      long totalUsedSpace = totalCapacity * 3 / 10;
      createFile(totalUsedSpace / numOfDatanodes, (short) numOfDatanodes);

      long newCapacity = CAPACITY;
      String newRack = RACK1;
      String newNodeGroup = NODEGROUP2;

      // start up an empty node with the same capacity and on the same rack
      cluster.startDataNodes(conf, 1, true, null, new String[]{newRack},
          new String[]{newNodeGroup}, new long[] {newCapacity});

      totalCapacity += newCapacity;

      // run balancer and validate results
      runBalancerCanFinish(conf, totalUsedSpace, totalCapacity);

      DatanodeInfo[] datanodeReport =
              client.getDatanodeReport(DatanodeReportType.ALL);

      Map<String, Integer> rackToUsedCapacity = new HashMap<String, Integer>();
      for (DatanodeInfo datanode: datanodeReport) {
        String rack = NetworkTopology.getFirstHalf(datanode.getNetworkLocation());
        int usedCapacity = (int) datanode.getDfsUsed();

        if (rackToUsedCapacity.get(rack) != null) {
          rackToUsedCapacity.put(rack, usedCapacity + rackToUsedCapacity.get(rack));
        } else {
          rackToUsedCapacity.put(rack, usedCapacity);
        }
      }
      assertEquals(rackToUsedCapacity.size(), 2);
      assertEquals(rackToUsedCapacity.get(RACK0), rackToUsedCapacity.get(RACK1));

    } finally {
      cluster.shutdown();
    }
  }

  /** Create a cluster with even distribution, and a new empty node is added to
   *  the cluster, then test rack locality for balancer policy.
   **/
  @Test(timeout=60000)
  public void testBalancerWithNodeGroup() throws Exception {
    Configuration conf = createConf();
    long[] capacities = new long[]{CAPACITY, CAPACITY};
    String[] racks = new String[]{RACK0, RACK1};
    String[] nodeGroups = new String[]{NODEGROUP0, NODEGROUP1};

    int numOfDatanodes = capacities.length;
    assertEquals(numOfDatanodes, racks.length);
    MiniDFSClusterWithNodeGroup.setNodeGroups(nodeGroups);
    cluster = new MiniDFSClusterWithNodeGroup(0, conf, capacities.length,
        true, true, null, racks, capacities);
    try {
      cluster.waitActive();
      client = DFSClient.createNamenode(conf);

      long totalCapacity = 0L;
      for(long capacity : capacities) {
        totalCapacity += capacity;
      }

      // fill up the cluster to be 30% full
      long totalUsedSpace = totalCapacity*3/10;

      createFile(totalUsedSpace / numOfDatanodes, (short) numOfDatanodes);

      long newCapacity = CAPACITY;
      String newRack = RACK1;
      String newNodeGroup = NODEGROUP2;
      // start up an empty node with the same capacity and on the same rack
      cluster.startDataNodes(conf, 1, true, null, new String[]{newRack},
          new String[]{newNodeGroup}, new long[] {newCapacity});

      totalCapacity += newCapacity;

      // run balancer and validate results
      runBalancer(conf, totalUsedSpace, totalCapacity);

    } finally {
      cluster.shutdown();
    }
  }

}