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HBASE-26712 Balancer encounters NPE in rare case (#4092)
Signed-off-by: Viraj Jasani <vjasani@apache.org>
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comnetwork committed Feb 16, 2022
1 parent 1b47575 commit 8ddd1d0f9e6be4cf969a7a12b015a07b88b2cfd2
Showing 3 changed files with 233 additions and 3 deletions.
@@ -365,6 +365,7 @@ public class HMaster extends HBaseServerBase<MasterRpcServices> implements Maste

private RSGroupBasedLoadBalancer balancer;
private BalancerChore balancerChore;
private static boolean disableBalancerChoreForTest = false;
private RegionNormalizerManager regionNormalizerManager;
private ClusterStatusChore clusterStatusChore;
private ClusterStatusPublisher clusterStatusPublisherChore = null;
@@ -1103,7 +1104,9 @@ private void finishActiveMasterInitialization(MonitoredTask status) throws IOExc
this.clusterStatusChore = new ClusterStatusChore(this, balancer);
getChoreService().scheduleChore(clusterStatusChore);
this.balancerChore = new BalancerChore(this);
getChoreService().scheduleChore(balancerChore);
if (!disableBalancerChoreForTest) {
getChoreService().scheduleChore(balancerChore);
}
if (regionNormalizerManager != null) {
getChoreService().scheduleChore(regionNormalizerManager.getRegionNormalizerChore());
}
@@ -4135,4 +4138,23 @@ public List<HRegionLocation> getMetaLocations() {
public Collection<ServerName> getLiveRegionServers() {
return regionServerTracker.getRegionServers();
}

@RestrictedApi(explanation = "Should only be called in tests", link = "",
allowedOnPath = ".*/src/test/.*")
void setLoadBalancer(RSGroupBasedLoadBalancer loadBalancer) {
this.balancer = loadBalancer;
}

@RestrictedApi(explanation = "Should only be called in tests", link = "",
allowedOnPath = ".*/src/test/.*")
void setAssignmentManager(AssignmentManager assignmentManager) {
this.assignmentManager = assignmentManager;
}

@RestrictedApi(explanation = "Should only be called in tests", link = "",
allowedOnPath = ".*/src/test/.*")
static void setDisableBalancerChoreForTest(boolean disable) {
disableBalancerChoreForTest = disable;
}

}
@@ -829,9 +829,9 @@ public Future<byte[]> moveAsync(RegionPlan regionPlan) throws HBaseIOException {
public Future<byte[]> balance(RegionPlan regionPlan) throws HBaseIOException {
ServerName current =
this.getRegionStates().getRegionAssignments().get(regionPlan.getRegionInfo());
if (!current.equals(regionPlan.getSource())) {
if (current == null || !current.equals(regionPlan.getSource())) {
LOG.debug("Skip region plan {}, source server not match, current region location is {}",
regionPlan, current);
regionPlan, current == null ? "(null)" : current);
return null;
}
return moveAsync(regionPlan);
@@ -0,0 +1,208 @@
/**
* 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.hbase.master;

import static org.junit.Assert.assertTrue;

import java.io.IOException;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.List;
import java.util.Map;
import java.util.concurrent.CyclicBarrier;
import java.util.concurrent.atomic.AtomicReference;

import org.apache.hadoop.hbase.HBaseClassTestRule;
import org.apache.hadoop.hbase.HBaseTestingUtil;
import org.apache.hadoop.hbase.ServerName;
import org.apache.hadoop.hbase.TableName;
import org.apache.hadoop.hbase.client.RegionInfo;
import org.apache.hadoop.hbase.master.assignment.AssignmentManager;
import org.apache.hadoop.hbase.rsgroup.RSGroupBasedLoadBalancer;
import org.apache.hadoop.hbase.testclassification.MasterTests;
import org.apache.hadoop.hbase.testclassification.MediumTests;
import org.apache.hadoop.hbase.util.Bytes;
import org.junit.After;
import org.junit.Before;
import org.junit.ClassRule;
import org.junit.Rule;
import org.junit.Test;
import org.junit.experimental.categories.Category;
import org.junit.rules.TestName;
import org.mockito.Mockito;
import org.mockito.invocation.InvocationOnMock;

@Category({ MasterTests.class, MediumTests.class })
public class TestMasterBalancerNPE {

@ClassRule
public static final HBaseClassTestRule CLASS_RULE =
HBaseClassTestRule.forClass(TestMasterBalancerNPE.class);

private static final HBaseTestingUtil TEST_UTIL = new HBaseTestingUtil();
private static final byte[] FAMILYNAME = Bytes.toBytes("fam");
@Rule
public TestName name = new TestName();

@Before
public void setupConfiguration() {
/**
* Make {@link BalancerChore} not run,so does not disrupt the test.
*/
HMaster.setDisableBalancerChoreForTest(true);
}

@After
public void shutdown() throws Exception {
HMaster.setDisableBalancerChoreForTest(false);
TEST_UTIL.shutdownMiniCluster();
}

/**
* This test is for HBASE-26712, to make the region is unassigned just before
* {@link AssignmentManager#balance} is invoked on the region.
*/
@Test
public void testBalancerNPE() throws Exception {
TEST_UTIL.startMiniCluster(2);
TEST_UTIL.getAdmin().balancerSwitch(false, true);
TableName tableName = createTable(name.getMethodName());
final HMaster master = TEST_UTIL.getHBaseCluster().getMaster();
List<RegionInfo> regionInfos = TEST_UTIL.getAdmin().getRegions(tableName);
assertTrue(regionInfos.size() == 1);
final ServerName serverName1 =
TEST_UTIL.getMiniHBaseCluster().getRegionServer(0).getServerName();
final ServerName serverName2 =
TEST_UTIL.getMiniHBaseCluster().getRegionServer(1).getServerName();

final RegionInfo regionInfo = regionInfos.get(0);

RSGroupBasedLoadBalancer loadBalancer = master.getLoadBalancer();
RSGroupBasedLoadBalancer spiedLoadBalancer = Mockito.spy(loadBalancer);
final AtomicReference<RegionPlan> regionPlanRef = new AtomicReference<RegionPlan>();

/**
* Mock {@link RSGroupBasedLoadBalancer#balanceCluster} to return the {@link RegionPlan} to move
* the only region to the other RegionServer.
*/
Mockito.doAnswer((InvocationOnMock invocation) -> {
@SuppressWarnings("unchecked")
Map<TableName, Map<ServerName, List<RegionInfo>>> tableNameToRegionServerNameToRegionInfos =
(Map<TableName, Map<ServerName, List<RegionInfo>>>) invocation.getArgument(0);
Map<ServerName, List<RegionInfo>> regionServerNameToRegionInfos =
tableNameToRegionServerNameToRegionInfos.get(tableName);
assertTrue(regionServerNameToRegionInfos.size() == 2);
List<ServerName> assignedRegionServerNames = new ArrayList<ServerName>();
for (Map.Entry<ServerName, List<RegionInfo>> entry : regionServerNameToRegionInfos
.entrySet()) {
if (entry.getValue().size() > 0) {
assignedRegionServerNames.add(entry.getKey());
}
}
assertTrue(assignedRegionServerNames.size() == 1);
ServerName assignedRegionServerName = assignedRegionServerNames.get(0);
ServerName notAssignedRegionServerName =
assignedRegionServerName.equals(serverName1) ? serverName2 : serverName1;
RegionPlan regionPlan =
new RegionPlan(regionInfo, assignedRegionServerName, notAssignedRegionServerName);
regionPlanRef.set(regionPlan);
return Arrays.asList(regionPlan);
}).when(spiedLoadBalancer).balanceCluster(Mockito.anyMap());

AssignmentManager assignmentManager = master.getAssignmentManager();
final AssignmentManager spiedAssignmentManager = Mockito.spy(assignmentManager);
final CyclicBarrier cyclicBarrier = new CyclicBarrier(2);

/**
* Override {@link AssignmentManager#balance} to invoke real {@link AssignmentManager#balance}
* after the region is successfully unassigned.
*/
Mockito.doAnswer((InvocationOnMock invocation) -> {
RegionPlan regionPlan = invocation.getArgument(0);
RegionPlan referedRegionPlan = regionPlanRef.get();
assertTrue(referedRegionPlan != null);
if (referedRegionPlan.equals(regionPlan)) {
/**
* To make {@link AssignmentManager#unassign} could be invoked just before
* {@link AssignmentManager#balance} is invoked.
*/
cyclicBarrier.await();
/**
* After {@link AssignmentManager#unassign} is completed,we could invoke
* {@link AssignmentManager#balance}.
*/
cyclicBarrier.await();
}
/**
* Before HBASE-26712,here may throw NPE.
*/
return invocation.callRealMethod();
}).when(spiedAssignmentManager).balance(Mockito.any());


try {
final AtomicReference<Throwable> exceptionRef = new AtomicReference<Throwable>(null);
Thread unassignThread = new Thread(() -> {
try {
/**
* To invoke {@link AssignmentManager#unassign} just before
* {@link AssignmentManager#balance} is invoked.
*/
cyclicBarrier.await();
spiedAssignmentManager.unassign(regionInfo);
assertTrue(spiedAssignmentManager.getRegionStates().getRegionAssignments()
.get(regionInfo) == null);
/**
* After {@link AssignmentManager#unassign} is completed,we could invoke
* {@link AssignmentManager#balance}.
*/
cyclicBarrier.await();
} catch (Exception e) {
exceptionRef.set(e);
}
});
unassignThread.setName("UnassignThread");
unassignThread.start();

master.setLoadBalancer(spiedLoadBalancer);
master.setAssignmentManager(spiedAssignmentManager);
/**
* enable balance
*/
TEST_UTIL.getAdmin().balancerSwitch(true, false);
/**
* Before HBASE-26712,here invokes {@link AssignmentManager#balance(RegionPlan)}
* which may throw NPE.
*/
master.balanceOrUpdateMetrics();

unassignThread.join();
assertTrue(exceptionRef.get() == null);
} finally {
master.setLoadBalancer(loadBalancer);
master.setAssignmentManager(assignmentManager);
}
}

private TableName createTable(String table) throws IOException {
TableName tableName = TableName.valueOf(table);
TEST_UTIL.createTable(tableName, FAMILYNAME);
return tableName;
}

}

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