helix-core/src/test/java/org/apache/helix/integration/rebalancer/WagedRebalancer/TestNodeSwap.java - helix - Git at Google

 package org.apache.helix.integration.rebalancer.WagedRebalancer;

 /*
  * 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.
  */

 import java.util.ArrayList;
 import java.util.Collections;
 import java.util.HashMap;
 import java.util.HashSet;
 import java.util.Iterator;
 import java.util.List;
 import java.util.Map;
 import java.util.Set;

 import org.apache.helix.ConfigAccessor;
 import org.apache.helix.common.ZkTestBase;
 import org.apache.helix.integration.manager.ClusterControllerManager;
 import org.apache.helix.integration.manager.MockParticipantManager;
 import org.apache.helix.model.BuiltInStateModelDefinitions;
 import org.apache.helix.model.ClusterConfig;
 import org.apache.helix.model.ExternalView;
 import org.apache.helix.model.InstanceConfig;
 import org.apache.helix.tools.ClusterVerifiers.HelixClusterVerifier;
 import org.apache.helix.tools.ClusterVerifiers.StrictMatchExternalViewVerifier;
 import org.testng.Assert;
 import org.testng.annotations.AfterClass;
 import org.testng.annotations.BeforeClass;
 import org.testng.annotations.Test;

 public class TestNodeSwap extends ZkTestBase {
   final int NUM_NODE = 6;
   protected static final int START_PORT = 12918;
   protected static final int _PARTITIONS = 20;

   protected final String CLASS_NAME = getShortClassName();
   protected final String CLUSTER_NAME = CLUSTER_PREFIX + "_" + CLASS_NAME;
   protected ClusterControllerManager _controller;
   protected HelixClusterVerifier _clusterVerifier;

   List<MockParticipantManager> _participants = new ArrayList<>();
   Set<String> _allDBs = new HashSet<>();
   int _replica = 3;

   String[] _testModels = { BuiltInStateModelDefinitions.OnlineOffline.name(),
       BuiltInStateModelDefinitions.MasterSlave.name(),
       BuiltInStateModelDefinitions.LeaderStandby.name()
   };

   @BeforeClass
   public void beforeClass() throws Exception {
     _gSetupTool.addCluster(CLUSTER_NAME, true);

     ConfigAccessor configAccessor = new ConfigAccessor(_gZkClient);
     ClusterConfig clusterConfig = configAccessor.getClusterConfig(CLUSTER_NAME);
     clusterConfig.setTopology("/zone/instance");
     clusterConfig.setFaultZoneType("zone");
     clusterConfig.setDelayRebalaceEnabled(true);
     // Set a long enough time to ensure delayed rebalance is activate
     clusterConfig.setRebalanceDelayTime(3000000);
     configAccessor.setClusterConfig(CLUSTER_NAME, clusterConfig);

     Set<String> nodes = new HashSet<>();
     for (int i = 0; i < NUM_NODE; i++) {
       String storageNodeName = PARTICIPANT_PREFIX + "_" + (START_PORT + i);
       _gSetupTool.addInstanceToCluster(CLUSTER_NAME, storageNodeName);
       String zone = "zone-" + i % 3;
       String domain = String.format("zone=%s,instance=%s", zone, storageNodeName);

       InstanceConfig instanceConfig =
           configAccessor.getInstanceConfig(CLUSTER_NAME, storageNodeName);
       instanceConfig.setDomain(domain);
       _gSetupTool.getClusterManagementTool()
           .setInstanceConfig(CLUSTER_NAME, storageNodeName, instanceConfig);
       nodes.add(storageNodeName);
     }

     // start dummy participants
     for (String node : nodes) {
       MockParticipantManager participant = new MockParticipantManager(ZK_ADDR, CLUSTER_NAME, node);
       participant.syncStart();
       _participants.add(participant);
     }

     // start controller
     String controllerName = CONTROLLER_PREFIX + "_0";
     _controller = new ClusterControllerManager(ZK_ADDR, CLUSTER_NAME, controllerName);
     _controller.syncStart();

     enablePersistBestPossibleAssignment(_gZkClient, CLUSTER_NAME, true);
     enableTopologyAwareRebalance(_gZkClient, CLUSTER_NAME, true);

     int i = 0;
     for (String stateModel : _testModels) {
       String db = "Test-DB-" + i++;
       createResourceWithWagedRebalance(CLUSTER_NAME, db, stateModel, _PARTITIONS, _replica,
           _replica - 1);
       _gSetupTool.rebalanceStorageCluster(CLUSTER_NAME, db, _replica);
       _allDBs.add(db);
     }
     Thread.sleep(1000);

     _clusterVerifier = new StrictMatchExternalViewVerifier.Builder(CLUSTER_NAME).setZkAddr(ZK_ADDR)
         .setResources(_allDBs).build();
     Assert.assertTrue(_clusterVerifier.verify(5000));
   }

   @AfterClass
   public void afterClass() throws Exception {
     _controller.syncStop();
     for (MockParticipantManager p : _participants) {
       p.syncStop();
     }
     deleteCluster(CLUSTER_NAME);
   }

   @Test
   public void testNodeSwap() throws Exception {
     Map<String, ExternalView> record = new HashMap<>();
     for (String db : _allDBs) {
       record.put(db,
           _gSetupTool.getClusterManagementTool().getResourceExternalView(CLUSTER_NAME, db));
     }
     ConfigAccessor configAccessor = new ConfigAccessor(_gZkClient);

     // 1. disable an old node
     MockParticipantManager oldParticipant = _participants.get(0);
     String oldParticipantName = oldParticipant.getInstanceName();
     final InstanceConfig instanceConfig =
         _gSetupTool.getClusterManagementTool().getInstanceConfig(CLUSTER_NAME, oldParticipantName);
     instanceConfig.setInstanceEnabled(false);
     _gSetupTool.getClusterManagementTool()
         .setInstanceConfig(CLUSTER_NAME, oldParticipantName, instanceConfig);
     Assert.assertTrue(_clusterVerifier.verify(10000));

     // 2. then entering maintenance mode and remove it from topology
     _gSetupTool.getClusterManagementTool()
         .manuallyEnableMaintenanceMode(CLUSTER_NAME, true, "NodeSwap", Collections.emptyMap());
     oldParticipant.syncStop();
     _participants.remove(oldParticipant);
     Thread.sleep(2000);
     _gSetupTool.getClusterManagementTool().dropInstance(CLUSTER_NAME, instanceConfig);

     // 3. create new participant with same topology
     String newParticipantName = "RandomParticipant_" + START_PORT;
     _gSetupTool.addInstanceToCluster(CLUSTER_NAME, newParticipantName);
     InstanceConfig newConfig = configAccessor.getInstanceConfig(CLUSTER_NAME, newParticipantName);
     String zone = instanceConfig.getDomainAsMap().get("zone");
     String domain = String.format("zone=%s,instance=%s", zone, newParticipantName);
     newConfig.setDomain(domain);
     _gSetupTool.getClusterManagementTool()
         .setInstanceConfig(CLUSTER_NAME, newParticipantName, newConfig);

     MockParticipantManager participant =
         new MockParticipantManager(ZK_ADDR, CLUSTER_NAME, newParticipantName);
     participant.syncStart();
     _participants.add(0, participant);

     // 4. exit maintenance mode and rebalance
     _gSetupTool.getClusterManagementTool()
         .manuallyEnableMaintenanceMode(CLUSTER_NAME, false, "NodeSwapDone", Collections.emptyMap());

     Thread.sleep(2000);
     _clusterVerifier = new StrictMatchExternalViewVerifier.Builder(CLUSTER_NAME).setZkAddr(ZK_ADDR)
         .setResources(_allDBs).build();
     Assert.assertTrue(_clusterVerifier.verify(5000));

     // Since only one node temporary down, the same partitions will be moved to the newly added node.
     for (String db : _allDBs) {
       ExternalView ev =
           _gSetupTool.getClusterManagementTool().getResourceExternalView(CLUSTER_NAME, db);
       ExternalView oldEv = record.get(db);
       for (String partition : ev.getPartitionSet()) {
         Map<String, String> stateMap = ev.getStateMap(partition);
         Map<String, String> oldStateMap = oldEv.getStateMap(partition);
         Assert.assertTrue(oldStateMap != null && stateMap != null);
         Assert.assertEquals(stateMap.size(), _replica);
         // Note the WAGED rebalanacer won't ensure the same state, because moving the top states
         // back to the replaced node might be unnecessary and causing overhead.
         Set<String> instanceSet = new HashSet<>(stateMap.keySet());
         if (instanceSet.remove(newParticipantName)) {
           instanceSet.add(oldParticipantName);
         }
         Assert.assertEquals(oldStateMap.keySet(), instanceSet);
       }
     }
   }

   @Test(dependsOnMethods = "testNodeSwap")
   public void testFaultZoneSwap() throws Exception {
     Map<String, ExternalView> record = new HashMap<>();
     for (String db : _allDBs) {
       record.put(db,
           _gSetupTool.getClusterManagementTool().getResourceExternalView(CLUSTER_NAME, db));
     }
     ConfigAccessor configAccessor = new ConfigAccessor(_gZkClient);

     // 1. disable a whole fault zone
     Map<String, InstanceConfig> removedInstanceConfigMap = new HashMap<>();
     for (MockParticipantManager participant : _participants) {
       String instanceName = participant.getInstanceName();
       InstanceConfig instanceConfig =
           _gSetupTool.getClusterManagementTool().getInstanceConfig(CLUSTER_NAME, instanceName);
       if (instanceConfig.getDomainAsMap().get("zone").equals("zone-0")) {
         instanceConfig.setInstanceEnabled(false);
         _gSetupTool.getClusterManagementTool()
             .setInstanceConfig(CLUSTER_NAME, instanceName, instanceConfig);
         removedInstanceConfigMap.put(instanceName, instanceConfig);
       }
     }
     Assert.assertTrue(_clusterVerifier.verify(10000));

     // 2. then entering maintenance mode and remove all the zone-0 nodes from topology
     _gSetupTool.getClusterManagementTool()
         .manuallyEnableMaintenanceMode(CLUSTER_NAME, true, "NodeSwap", Collections.emptyMap());
     Iterator<MockParticipantManager> iter = _participants.iterator();
     while(iter.hasNext()) {
       MockParticipantManager participant = iter.next();
       String instanceName = participant.getInstanceName();
       if (removedInstanceConfigMap.containsKey(instanceName)) {
         participant.syncStop();
         iter.remove();
         Thread.sleep(1000);
         _gSetupTool.getClusterManagementTool()
             .dropInstance(CLUSTER_NAME, removedInstanceConfigMap.get(instanceName));
       }
     }

     // 3. create new participants with same topology
     Set<String> newInstanceNames = new HashSet<>();
     for (int i = 0; i < removedInstanceConfigMap.size(); i++) {
       String newParticipantName = "NewParticipant_" + (START_PORT + i++);
       newInstanceNames.add(newParticipantName);
       _gSetupTool.addInstanceToCluster(CLUSTER_NAME, newParticipantName);
       InstanceConfig newConfig = configAccessor.getInstanceConfig(CLUSTER_NAME, newParticipantName);
       String domain = String.format("zone=zone-0,instance=%s", newParticipantName);
       newConfig.setDomain(domain);
       _gSetupTool.getClusterManagementTool()
           .setInstanceConfig(CLUSTER_NAME, newParticipantName, newConfig);

       MockParticipantManager participant =
           new MockParticipantManager(ZK_ADDR, CLUSTER_NAME, newParticipantName);
       participant.syncStart();
       _participants.add(participant);
     }

     // 4. exit maintenance mode and rebalance
     _gSetupTool.getClusterManagementTool()
         .manuallyEnableMaintenanceMode(CLUSTER_NAME, false, "NodeSwapDone", Collections.emptyMap());

     Thread.sleep(2000);
     _clusterVerifier = new StrictMatchExternalViewVerifier.Builder(CLUSTER_NAME).setZkAddr(ZK_ADDR)
         .setResources(_allDBs).build();
     Assert.assertTrue(_clusterVerifier.verify(5000));

     for (String db : _allDBs) {
       ExternalView ev =
           _gSetupTool.getClusterManagementTool().getResourceExternalView(CLUSTER_NAME, db);
       ExternalView oldEv = record.get(db);
       for (String partition : ev.getPartitionSet()) {
         Map<String, String> stateMap = ev.getStateMap(partition);
         Map<String, String> oldStateMap = oldEv.getStateMap(partition);
         Assert.assertTrue(oldStateMap != null && stateMap != null);
         Assert.assertEquals(stateMap.size(), _replica);
         Set<String> instanceSet = new HashSet<>(stateMap.keySet());
         instanceSet.removeAll(oldStateMap.keySet());
         // All the different instances in the new mapping are the newly added instance
         Assert.assertTrue(newInstanceNames.containsAll(instanceSet));
         instanceSet = new HashSet<>(oldStateMap.keySet());
         instanceSet.removeAll(stateMap.keySet());
         // All the different instances in the old mapping are the removed instance
         Assert.assertTrue(removedInstanceConfigMap.keySet().containsAll(instanceSet));
       }
     }
   }
 }
	package org.apache.helix.integration.rebalancer.WagedRebalancer;

	/*
	* 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.
	*/

	import java.util.ArrayList;
	import java.util.Collections;
	import java.util.HashMap;
	import java.util.HashSet;
	import java.util.Iterator;
	import java.util.List;
	import java.util.Map;
	import java.util.Set;

	import org.apache.helix.ConfigAccessor;
	import org.apache.helix.common.ZkTestBase;
	import org.apache.helix.integration.manager.ClusterControllerManager;
	import org.apache.helix.integration.manager.MockParticipantManager;
	import org.apache.helix.model.BuiltInStateModelDefinitions;
	import org.apache.helix.model.ClusterConfig;
	import org.apache.helix.model.ExternalView;
	import org.apache.helix.model.InstanceConfig;
	import org.apache.helix.tools.ClusterVerifiers.HelixClusterVerifier;
	import org.apache.helix.tools.ClusterVerifiers.StrictMatchExternalViewVerifier;
	import org.testng.Assert;
	import org.testng.annotations.AfterClass;
	import org.testng.annotations.BeforeClass;
	import org.testng.annotations.Test;

	public class TestNodeSwap extends ZkTestBase {
	final int NUM_NODE = 6;
	protected static final int START_PORT = 12918;
	protected static final int _PARTITIONS = 20;

	protected final String CLASS_NAME = getShortClassName();
	protected final String CLUSTER_NAME = CLUSTER_PREFIX + "_" + CLASS_NAME;
	protected ClusterControllerManager _controller;
	protected HelixClusterVerifier _clusterVerifier;

	List<MockParticipantManager> _participants = new ArrayList<>();
	Set<String> _allDBs = new HashSet<>();
	int _replica = 3;

	String[] _testModels = { BuiltInStateModelDefinitions.OnlineOffline.name(),
	BuiltInStateModelDefinitions.MasterSlave.name(),
	BuiltInStateModelDefinitions.LeaderStandby.name()
	};

	@BeforeClass
	public void beforeClass() throws Exception {
	_gSetupTool.addCluster(CLUSTER_NAME, true);

	ConfigAccessor configAccessor = new ConfigAccessor(_gZkClient);
	ClusterConfig clusterConfig = configAccessor.getClusterConfig(CLUSTER_NAME);
	clusterConfig.setTopology("/zone/instance");
	clusterConfig.setFaultZoneType("zone");
	clusterConfig.setDelayRebalaceEnabled(true);
	// Set a long enough time to ensure delayed rebalance is activate
	clusterConfig.setRebalanceDelayTime(3000000);
	configAccessor.setClusterConfig(CLUSTER_NAME, clusterConfig);

	Set<String> nodes = new HashSet<>();
	for (int i = 0; i < NUM_NODE; i++) {
	String storageNodeName = PARTICIPANT_PREFIX + "_" + (START_PORT + i);
	_gSetupTool.addInstanceToCluster(CLUSTER_NAME, storageNodeName);
	String zone = "zone-" + i % 3;
	String domain = String.format("zone=%s,instance=%s", zone, storageNodeName);

	InstanceConfig instanceConfig =
	configAccessor.getInstanceConfig(CLUSTER_NAME, storageNodeName);
	instanceConfig.setDomain(domain);
	_gSetupTool.getClusterManagementTool()
	.setInstanceConfig(CLUSTER_NAME, storageNodeName, instanceConfig);
	nodes.add(storageNodeName);
	}

	// start dummy participants
	for (String node : nodes) {
	MockParticipantManager participant = new MockParticipantManager(ZK_ADDR, CLUSTER_NAME, node);
	participant.syncStart();
	_participants.add(participant);
	}

	// start controller
	String controllerName = CONTROLLER_PREFIX + "_0";
	_controller = new ClusterControllerManager(ZK_ADDR, CLUSTER_NAME, controllerName);
	_controller.syncStart();

	enablePersistBestPossibleAssignment(_gZkClient, CLUSTER_NAME, true);
	enableTopologyAwareRebalance(_gZkClient, CLUSTER_NAME, true);

	int i = 0;
	for (String stateModel : _testModels) {
	String db = "Test-DB-" + i++;
	createResourceWithWagedRebalance(CLUSTER_NAME, db, stateModel, _PARTITIONS, _replica,
	_replica - 1);
	_gSetupTool.rebalanceStorageCluster(CLUSTER_NAME, db, _replica);
	_allDBs.add(db);
	}
	Thread.sleep(1000);

	_clusterVerifier = new StrictMatchExternalViewVerifier.Builder(CLUSTER_NAME).setZkAddr(ZK_ADDR)
	.setResources(_allDBs).build();
	Assert.assertTrue(_clusterVerifier.verify(5000));
	}

	@AfterClass
	public void afterClass() throws Exception {
	_controller.syncStop();
	for (MockParticipantManager p : _participants) {
	p.syncStop();
	}
	deleteCluster(CLUSTER_NAME);
	}

	@Test
	public void testNodeSwap() throws Exception {
	Map<String, ExternalView> record = new HashMap<>();
	for (String db : _allDBs) {
	record.put(db,
	_gSetupTool.getClusterManagementTool().getResourceExternalView(CLUSTER_NAME, db));
	}
	ConfigAccessor configAccessor = new ConfigAccessor(_gZkClient);

	// 1. disable an old node
	MockParticipantManager oldParticipant = _participants.get(0);
	String oldParticipantName = oldParticipant.getInstanceName();
	final InstanceConfig instanceConfig =
	_gSetupTool.getClusterManagementTool().getInstanceConfig(CLUSTER_NAME, oldParticipantName);
	instanceConfig.setInstanceEnabled(false);
	_gSetupTool.getClusterManagementTool()
	.setInstanceConfig(CLUSTER_NAME, oldParticipantName, instanceConfig);
	Assert.assertTrue(_clusterVerifier.verify(10000));

	// 2. then entering maintenance mode and remove it from topology
	_gSetupTool.getClusterManagementTool()
	.manuallyEnableMaintenanceMode(CLUSTER_NAME, true, "NodeSwap", Collections.emptyMap());
	oldParticipant.syncStop();
	_participants.remove(oldParticipant);
	Thread.sleep(2000);
	_gSetupTool.getClusterManagementTool().dropInstance(CLUSTER_NAME, instanceConfig);

	// 3. create new participant with same topology
	String newParticipantName = "RandomParticipant_" + START_PORT;
	_gSetupTool.addInstanceToCluster(CLUSTER_NAME, newParticipantName);
	InstanceConfig newConfig = configAccessor.getInstanceConfig(CLUSTER_NAME, newParticipantName);
	String zone = instanceConfig.getDomainAsMap().get("zone");
	String domain = String.format("zone=%s,instance=%s", zone, newParticipantName);
	newConfig.setDomain(domain);
	_gSetupTool.getClusterManagementTool()
	.setInstanceConfig(CLUSTER_NAME, newParticipantName, newConfig);

	MockParticipantManager participant =
	new MockParticipantManager(ZK_ADDR, CLUSTER_NAME, newParticipantName);
	participant.syncStart();
	_participants.add(0, participant);

	// 4. exit maintenance mode and rebalance
	_gSetupTool.getClusterManagementTool()
	.manuallyEnableMaintenanceMode(CLUSTER_NAME, false, "NodeSwapDone", Collections.emptyMap());

	Thread.sleep(2000);
	_clusterVerifier = new StrictMatchExternalViewVerifier.Builder(CLUSTER_NAME).setZkAddr(ZK_ADDR)
	.setResources(_allDBs).build();
	Assert.assertTrue(_clusterVerifier.verify(5000));

	// Since only one node temporary down, the same partitions will be moved to the newly added node.
	for (String db : _allDBs) {
	ExternalView ev =
	_gSetupTool.getClusterManagementTool().getResourceExternalView(CLUSTER_NAME, db);
	ExternalView oldEv = record.get(db);
	for (String partition : ev.getPartitionSet()) {
	Map<String, String> stateMap = ev.getStateMap(partition);
	Map<String, String> oldStateMap = oldEv.getStateMap(partition);
	Assert.assertTrue(oldStateMap != null && stateMap != null);
	Assert.assertEquals(stateMap.size(), _replica);
	// Note the WAGED rebalanacer won't ensure the same state, because moving the top states
	// back to the replaced node might be unnecessary and causing overhead.
	Set<String> instanceSet = new HashSet<>(stateMap.keySet());
	if (instanceSet.remove(newParticipantName)) {
	instanceSet.add(oldParticipantName);
	}
	Assert.assertEquals(oldStateMap.keySet(), instanceSet);
	}
	}
	}

	@Test(dependsOnMethods = "testNodeSwap")
	public void testFaultZoneSwap() throws Exception {
	Map<String, ExternalView> record = new HashMap<>();
	for (String db : _allDBs) {
	record.put(db,
	_gSetupTool.getClusterManagementTool().getResourceExternalView(CLUSTER_NAME, db));
	}
	ConfigAccessor configAccessor = new ConfigAccessor(_gZkClient);

	// 1. disable a whole fault zone
	Map<String, InstanceConfig> removedInstanceConfigMap = new HashMap<>();
	for (MockParticipantManager participant : _participants) {
	String instanceName = participant.getInstanceName();
	InstanceConfig instanceConfig =
	_gSetupTool.getClusterManagementTool().getInstanceConfig(CLUSTER_NAME, instanceName);
	if (instanceConfig.getDomainAsMap().get("zone").equals("zone-0")) {
	instanceConfig.setInstanceEnabled(false);
	_gSetupTool.getClusterManagementTool()
	.setInstanceConfig(CLUSTER_NAME, instanceName, instanceConfig);
	removedInstanceConfigMap.put(instanceName, instanceConfig);
	}
	}
	Assert.assertTrue(_clusterVerifier.verify(10000));

	// 2. then entering maintenance mode and remove all the zone-0 nodes from topology
	_gSetupTool.getClusterManagementTool()
	.manuallyEnableMaintenanceMode(CLUSTER_NAME, true, "NodeSwap", Collections.emptyMap());
	Iterator<MockParticipantManager> iter = _participants.iterator();
	while(iter.hasNext()) {
	MockParticipantManager participant = iter.next();
	String instanceName = participant.getInstanceName();
	if (removedInstanceConfigMap.containsKey(instanceName)) {
	participant.syncStop();
	iter.remove();
	Thread.sleep(1000);
	_gSetupTool.getClusterManagementTool()
	.dropInstance(CLUSTER_NAME, removedInstanceConfigMap.get(instanceName));
	}
	}

	// 3. create new participants with same topology
	Set<String> newInstanceNames = new HashSet<>();
	for (int i = 0; i < removedInstanceConfigMap.size(); i++) {
	String newParticipantName = "NewParticipant_" + (START_PORT + i++);
	newInstanceNames.add(newParticipantName);
	_gSetupTool.addInstanceToCluster(CLUSTER_NAME, newParticipantName);
	InstanceConfig newConfig = configAccessor.getInstanceConfig(CLUSTER_NAME, newParticipantName);
	String domain = String.format("zone=zone-0,instance=%s", newParticipantName);
	newConfig.setDomain(domain);
	_gSetupTool.getClusterManagementTool()
	.setInstanceConfig(CLUSTER_NAME, newParticipantName, newConfig);

	MockParticipantManager participant =
	new MockParticipantManager(ZK_ADDR, CLUSTER_NAME, newParticipantName);
	participant.syncStart();
	_participants.add(participant);
	}

	// 4. exit maintenance mode and rebalance
	_gSetupTool.getClusterManagementTool()
	.manuallyEnableMaintenanceMode(CLUSTER_NAME, false, "NodeSwapDone", Collections.emptyMap());

	Thread.sleep(2000);
	_clusterVerifier = new StrictMatchExternalViewVerifier.Builder(CLUSTER_NAME).setZkAddr(ZK_ADDR)
	.setResources(_allDBs).build();
	Assert.assertTrue(_clusterVerifier.verify(5000));

	for (String db : _allDBs) {
	ExternalView ev =
	_gSetupTool.getClusterManagementTool().getResourceExternalView(CLUSTER_NAME, db);
	ExternalView oldEv = record.get(db);
	for (String partition : ev.getPartitionSet()) {
	Map<String, String> stateMap = ev.getStateMap(partition);
	Map<String, String> oldStateMap = oldEv.getStateMap(partition);
	Assert.assertTrue(oldStateMap != null && stateMap != null);
	Assert.assertEquals(stateMap.size(), _replica);
	Set<String> instanceSet = new HashSet<>(stateMap.keySet());
	instanceSet.removeAll(oldStateMap.keySet());
	// All the different instances in the new mapping are the newly added instance
	Assert.assertTrue(newInstanceNames.containsAll(instanceSet));
	instanceSet = new HashSet<>(oldStateMap.keySet());
	instanceSet.removeAll(stateMap.keySet());
	// All the different instances in the old mapping are the removed instance
	Assert.assertTrue(removedInstanceConfigMap.keySet().containsAll(instanceSet));
	}
	}
	}
	}