Merge branch 'trunk' into HDFS-6581

hadoop-hdfs-project/hadoop-hdfs/CHANGES.txt

@@ -780,6 +780,9 @@ Release 2.6.0 - UNRELEASED
 
     HDFS-4227. Document dfs.namenode.resource.*  (Daisuke Kobayashi via aw)
 
+    HDFS-6754. TestNamenodeCapacityReport may sometimes fail due to lack of
+    retry. (Mit Desai via kihwal)
+
     BREAKDOWN OF HDFS-6134 AND HADOOP-10150 SUBTASKS AND RELATED JIRAS
   
       HDFS-6387. HDFS CLI admin tool for creating & deleting an

hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/server/namenode/TestNamenodeCapacityReport.java

@@ -169,8 +169,8 @@ public class TestNamenodeCapacityReport {
   @Test
   public void testXceiverCount() throws Exception {
     Configuration conf = new HdfsConfiguration();
-    // don't waste time retrying if close fails
-    conf.setInt(DFS_CLIENT_BLOCK_WRITE_LOCATEFOLLOWINGBLOCK_RETRIES_KEY, 0);
+    // retry one time, if close fails
+    conf.setInt(DFS_CLIENT_BLOCK_WRITE_LOCATEFOLLOWINGBLOCK_RETRIES_KEY, 1);
     MiniDFSCluster cluster = null;
 
     final int nodes = 8;

hadoop-yarn-project/CHANGES.txt

@@ -32,6 +32,9 @@ Release 2.7.0 - UNRELEASED
   INCOMPATIBLE CHANGES
 
   NEW FEATURES
+  
+    YARN-2179. [YARN-1492] Initial cache manager structure and context. 
+    (Chris Trezzo via kasha) 
 
   IMPROVEMENTS
 

hadoop-yarn-project/hadoop-yarn/bin/yarn

@@ -33,6 +33,7 @@ function hadoop_usage
   echo "  resourcemanager                       run the ResourceManager"
   echo "  resourcemanager -format-state-store   deletes the RMStateStore"
   echo "  rmadmin                               admin tools"
+  echo "  sharedcachemanager                    run the SharedCacheManager daemon"
   echo "  timelineserver                        run the timeline server"
   echo "  version                               print the version"
   echo " or"
@@ -149,6 +150,11 @@ case "${COMMAND}" in
       JAVA_HEAP_MAX="-Xmx${YARN_TIMELINESERVER_HEAPSIZE}m"
     fi
   ;;
+  sharedcachemanager)
+    daemon="true"
+    CLASS='org.apache.hadoop.yarn.server.sharedcachemanager.SharedCacheManager'
+    YARN_OPTS="$YARN_OPTS $YARN_SHAREDCACHEMANAGER_OPTS"
+  ;;
   version)
     CLASS=org.apache.hadoop.util.VersionInfo
     hadoop_debug "Append YARN_CLIENT_OPTS onto YARN_OPTS"

hadoop-yarn-project/hadoop-yarn/hadoop-yarn-api/src/main/java/org/apache/hadoop/yarn/conf/YarnConfiguration.java

@@ -1285,6 +1285,28 @@ public class YarnConfiguration extends Configuration {
   public static final boolean
       TIMELINE_SERVICE_HTTP_CROSS_ORIGIN_ENABLED_DEFAULT = false;
 
+  // ///////////////////////////////
+  // Shared Cache Configs
+  // ///////////////////////////////
+  public static final String SHARED_CACHE_PREFIX = "yarn.sharedcache.";
+
+  // common configs
+  /** whether the shared cache is enabled/disabled */
+  public static final String SHARED_CACHE_ENABLED =
+      SHARED_CACHE_PREFIX + "enabled";
+  public static final boolean DEFAULT_SHARED_CACHE_ENABLED = false;
+
+  /** The config key for the shared cache root directory. */
+  public static final String SHARED_CACHE_ROOT =
+      SHARED_CACHE_PREFIX + "root-dir";
+  public static final String DEFAULT_SHARED_CACHE_ROOT = "/sharedcache";
+
+  /** The config key for the level of nested directories before getting to the
+   * checksum directory. */
+  public static final String SHARED_CACHE_NESTED_LEVEL =
+      SHARED_CACHE_PREFIX + "nested-level";
+  public static final int DEFAULT_SHARED_CACHE_NESTED_LEVEL = 3;
+  
   ////////////////////////////////
   // Other Configs
   ////////////////////////////////

hadoop-yarn-project/hadoop-yarn/hadoop-yarn-common/src/main/resources/yarn-default.xml

@@ -1310,6 +1310,26 @@
     <value>/etc/krb5.keytab</value>
   </property>
 
+  <!--  Shared Cache Configuration -->
+  <property>
+    <description>Whether the shared cache is enabled</description>
+    <name>yarn.sharedcache.enabled</name>
+    <value>false</value>
+  </property>
+
+  <property>
+    <description>The root directory for the shared cache</description>
+    <name>yarn.sharedcache.root-dir</name>
+    <value>/sharedcache</value>
+  </property>
+
+  <property>
+    <description>The level of nested directories before getting to the checksum
+    directories. It must be non-negative.</description>
+    <name>yarn.sharedcache.nested-level</name>
+    <value>3</value>
+  </property>
+
   <!-- Other configuration -->
   <property>
     <description>The interval that the yarn client library uses to poll the

hadoop-yarn-project/hadoop-yarn/hadoop-yarn-server/hadoop-yarn-server-common/src/main/java/org/apache/hadoop/yarn/server/sharedcache/SharedCacheStructureUtil.java

@@ -0,0 +1,81 @@
+/**
+ * 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.yarn.server.sharedcache;
+
+import org.apache.commons.logging.Log;
+import org.apache.commons.logging.LogFactory;
+import org.apache.hadoop.classification.InterfaceAudience.Private;
+import org.apache.hadoop.classification.InterfaceStability.Unstable;
+import org.apache.hadoop.conf.Configuration;
+import org.apache.hadoop.fs.Path;
+import org.apache.hadoop.yarn.conf.YarnConfiguration;
+
+/**
+ * A utility class that contains helper methods for dealing with the internal
+ * shared cache structure.
+ */
+@Private
+@Unstable
+public class SharedCacheStructureUtil {
+
+  private static final Log LOG = LogFactory.getLog(SharedCacheStructureUtil.class);
+
+  @Private
+  public static int getCacheDepth(Configuration conf) {
+    int cacheDepth =
+        conf.getInt(YarnConfiguration.SHARED_CACHE_NESTED_LEVEL,
+            YarnConfiguration.DEFAULT_SHARED_CACHE_NESTED_LEVEL);
+
+    if (cacheDepth <= 0) {
+      LOG.warn("Specified cache depth was less than or equal to zero."
+          + " Using default value instead. Default: "
+          + YarnConfiguration.DEFAULT_SHARED_CACHE_NESTED_LEVEL
+          + ", Specified: " + cacheDepth);
+      cacheDepth = YarnConfiguration.DEFAULT_SHARED_CACHE_NESTED_LEVEL;
+    }
+
+    return cacheDepth;
+  }
+
+  @Private
+  public static String getCacheEntryPath(int cacheDepth, String cacheRoot,
+      String checksum) {
+
+    if (cacheDepth <= 0) {
+      throw new IllegalArgumentException(
+          "The cache depth must be greater than 0. Passed value: " + cacheDepth);
+    }
+    if (checksum.length() < cacheDepth) {
+      throw new IllegalArgumentException("The checksum passed was too short: "
+          + checksum);
+    }
+
+    // Build the cache entry path to the specified depth. For example, if the
+    // depth is 3 and the checksum is 3c4f, the path would be:
+    // SHARED_CACHE_ROOT/3/c/4/3c4f
+    StringBuilder sb = new StringBuilder(cacheRoot);
+    for (int i = 0; i < cacheDepth; i++) {
+      sb.append(Path.SEPARATOR_CHAR);
+      sb.append(checksum.charAt(i));
+    }
+    sb.append(Path.SEPARATOR_CHAR).append(checksum);
+
+    return sb.toString();
+  }
+}

hadoop-yarn-project/hadoop-yarn/hadoop-yarn-server/hadoop-yarn-server-sharedcachemanager/pom.xml

@@ -0,0 +1,90 @@
+<?xml version="1.0"?>
+<!--
+  Licensed 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. See accompanying LICENSE file.
+-->
+<project xmlns:pom="http://maven.apache.org/POM/4.0.0">
+  <modelVersion>4.0.0</modelVersion>
+  <parent>
+    <artifactId>hadoop-yarn-server</artifactId>
+    <groupId>org.apache.hadoop</groupId>
+    <version>3.0.0-SNAPSHOT</version>
+  </parent>
+  <groupId>org.apache.hadoop</groupId>
+  <artifactId>hadoop-yarn-server-sharedcachemanager</artifactId>
+  <version>3.0.0-SNAPSHOT</version>
+  <name>hadoop-yarn-server-sharedcachemanager</name>
+
+  <properties>
+    <!-- Needed for generating FindBugs warnings using parent pom -->
+    <yarn.basedir>${project.parent.parent.basedir}</yarn.basedir>
+  </properties>
+
+  <dependencies>
+    <dependency>
+      <groupId>org.apache.hadoop</groupId>
+      <artifactId>hadoop-common</artifactId>
+    </dependency>
+    <dependency>
+      <groupId>org.apache.hadoop</groupId>
+      <artifactId>hadoop-yarn-api</artifactId>
+    </dependency>
+    <dependency>
+      <groupId>org.apache.hadoop</groupId>
+      <artifactId>hadoop-yarn-common</artifactId>
+    </dependency>
+    <dependency>
+      <groupId>org.apache.hadoop</groupId>
+      <artifactId>hadoop-yarn-client</artifactId>
+    </dependency>
+    <dependency>
+      <groupId>junit</groupId>
+      <artifactId>junit</artifactId>
+      <scope>test</scope>
+    </dependency>
+    <dependency>
+      <groupId>org.mockito</groupId>
+      <artifactId>mockito-all</artifactId>
+      <scope>test</scope>
+    </dependency>
+    <dependency>
+      <groupId>org.apache.hadoop</groupId>
+      <artifactId>hadoop-common</artifactId>
+      <type>test-jar</type>
+      <scope>test</scope>
+    </dependency>
+    <dependency>
+      <groupId>org.apache.hadoop</groupId>
+      <artifactId>hadoop-yarn-server-tests</artifactId>
+      <scope>test</scope>
+      <type>test-jar</type>
+    </dependency>
+  </dependencies>
+  
+  <build>
+      <plugins>
+
+      <!-- Publish tests jar -->
+      <plugin>
+        <artifactId>maven-jar-plugin</artifactId>
+        <executions>
+          <execution>
+            <goals>
+              <goal>test-jar</goal>
+            </goals>
+            <phase>test-compile</phase>
+          </execution>
+        </executions>
+      </plugin>
+    </plugins>
+  </build>
+</project>

hadoop-yarn-project/hadoop-yarn/hadoop-yarn-server/hadoop-yarn-server-sharedcachemanager/src/main/java/org/apache/hadoop/yarn/server/sharedcachemanager/AppChecker.java

@@ -0,0 +1,65 @@
+/**
+ * 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.yarn.server.sharedcachemanager;
+
+import java.util.Collection;
+
+import org.apache.hadoop.classification.InterfaceAudience.Private;
+import org.apache.hadoop.classification.InterfaceStability.Evolving;
+import org.apache.hadoop.service.CompositeService;
+import org.apache.hadoop.yarn.api.records.ApplicationId;
+import org.apache.hadoop.yarn.exceptions.YarnException;
+
+/**
+ * An interface for checking whether an app is running so that the cleaner
+ * service may determine if it can safely remove a cached entry.
+ */
+@Private
+@Evolving
+public abstract class AppChecker extends CompositeService {
+
+  public AppChecker() {
+    super("AppChecker");
+  }
+
+  public AppChecker(String name) {
+    super(name);
+  }
+
+  /**
+   * Returns whether the app is in an active state.
+   * 
+   * @return true if the app is found and is not in one of the completed states;
+   *         false otherwise
+   * @throws YarnException if there is an error in determining the app state
+   */
+  @Private
+  public abstract boolean isApplicationActive(ApplicationId id)
+      throws YarnException;
+
+  /**
+   * Returns the list of all active apps at the given time.
+   * 
+   * @return the list of active apps, or an empty list if there is none
+   * @throws YarnException if there is an error in obtaining the list
+   */
+  @Private
+  public abstract Collection<ApplicationId> getActiveApplications()
+      throws YarnException;
+}

hadoop-yarn-project/hadoop-yarn/hadoop-yarn-server/hadoop-yarn-server-sharedcachemanager/src/main/java/org/apache/hadoop/yarn/server/sharedcachemanager/RemoteAppChecker.java

@@ -0,0 +1,102 @@
+/**
+ * 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.yarn.server.sharedcachemanager;
+
+import java.io.IOException;
+import java.util.ArrayList;
+import java.util.Collection;
+import java.util.EnumSet;
+import java.util.List;
+
+import org.apache.hadoop.classification.InterfaceAudience.Private;
+import org.apache.hadoop.classification.InterfaceStability.Unstable;
+import org.apache.hadoop.conf.Configuration;
+import org.apache.hadoop.yarn.api.records.ApplicationId;
+import org.apache.hadoop.yarn.api.records.ApplicationReport;
+import org.apache.hadoop.yarn.api.records.YarnApplicationState;
+import org.apache.hadoop.yarn.client.api.YarnClient;
+import org.apache.hadoop.yarn.exceptions.ApplicationNotFoundException;
+import org.apache.hadoop.yarn.exceptions.YarnException;
+
+/**
+ * An implementation of AppChecker that queries the resource manager remotely to
+ * determine whether the app is running.
+ */
+@Private
+@Unstable
+public class RemoteAppChecker extends AppChecker {
+
+  private static final EnumSet<YarnApplicationState> ACTIVE_STATES = EnumSet
+      .of(YarnApplicationState.NEW, YarnApplicationState.ACCEPTED,
+          YarnApplicationState.NEW_SAVING, YarnApplicationState.SUBMITTED,
+          YarnApplicationState.RUNNING);
+
+  private final YarnClient client;
+
+  public RemoteAppChecker() {
+    this(YarnClient.createYarnClient());
+  }
+
+  RemoteAppChecker(YarnClient client) {
+    super("RemoteAppChecker");
+    this.client = client;
+  }
+
+  @Override
+  protected void serviceInit(Configuration conf) throws Exception {
+    addService(client);
+    super.serviceInit(conf);
+  }
+
+  @Override
+  @Private
+  public boolean isApplicationActive(ApplicationId id) throws YarnException {
+    ApplicationReport report = null;
+    try {
+      report = client.getApplicationReport(id);
+    } catch (ApplicationNotFoundException e) {
+      // the app does not exist
+      return false;
+    } catch (IOException e) {
+      throw new YarnException(e);
+    }
+
+    if (report == null) {
+      // the app does not exist
+      return false;
+    }
+
+    return ACTIVE_STATES.contains(report.getYarnApplicationState());
+  }
+
+  @Override
+  @Private
+  public Collection<ApplicationId> getActiveApplications() throws YarnException {
+    try {
+      List<ApplicationId> activeApps = new ArrayList<ApplicationId>();
+      List<ApplicationReport> apps = client.getApplications(ACTIVE_STATES);
+      for (ApplicationReport app: apps) {
+        activeApps.add(app.getApplicationId());
+      }
+      return activeApps;
+    } catch (IOException e) {
+      throw new YarnException(e);
+    }
+  }
+}

hadoop-yarn-project/hadoop-yarn/hadoop-yarn-server/hadoop-yarn-server-sharedcachemanager/src/main/java/org/apache/hadoop/yarn/server/sharedcachemanager/SharedCacheManager.java

@@ -0,0 +1,86 @@
+/**
+ * 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.yarn.server.sharedcachemanager;
+
+import org.apache.commons.logging.Log;
+import org.apache.commons.logging.LogFactory;
+import org.apache.hadoop.classification.InterfaceAudience.Private;
+import org.apache.hadoop.classification.InterfaceStability.Unstable;
+import org.apache.hadoop.conf.Configuration;
+import org.apache.hadoop.metrics2.lib.DefaultMetricsSystem;
+import org.apache.hadoop.metrics2.source.JvmMetrics;
+import org.apache.hadoop.service.CompositeService;
+import org.apache.hadoop.util.ShutdownHookManager;
+import org.apache.hadoop.util.StringUtils;
+import org.apache.hadoop.yarn.YarnUncaughtExceptionHandler;
+import org.apache.hadoop.yarn.conf.YarnConfiguration;
+
+/**
+ * This service maintains the shared cache meta data. It handles claiming and
+ * releasing of resources, all rpc calls from the client to the shared cache
+ * manager, and administrative commands. It also persists the shared cache meta
+ * data to a backend store, and cleans up stale entries on a regular basis.
+ */
+@Private
+@Unstable
+public class SharedCacheManager extends CompositeService {
+  /**
+   * Priority of the SharedCacheManager shutdown hook.
+   */
+  public static final int SHUTDOWN_HOOK_PRIORITY = 30;
+
+  private static final Log LOG = LogFactory.getLog(SharedCacheManager.class);
+
+  public SharedCacheManager() {
+    super("SharedCacheManager");
+  }
+
+  @Override
+  protected void serviceInit(Configuration conf) throws Exception {
+    // init metrics
+    DefaultMetricsSystem.initialize("SharedCacheManager");
+    JvmMetrics.initSingleton("SharedCacheManager", null);
+
+    super.serviceInit(conf);
+  }
+
+  @Override
+  protected void serviceStop() throws Exception {
+
+    DefaultMetricsSystem.shutdown();
+    super.serviceStop();
+  }
+
+  public static void main(String[] args) {
+    Thread.setDefaultUncaughtExceptionHandler(new YarnUncaughtExceptionHandler());
+    StringUtils.startupShutdownMessage(SharedCacheManager.class, args, LOG);
+    try {
+      Configuration conf = new YarnConfiguration();
+      SharedCacheManager sharedCacheManager = new SharedCacheManager();
+      ShutdownHookManager.get().addShutdownHook(
+          new CompositeServiceShutdownHook(sharedCacheManager),
+          SHUTDOWN_HOOK_PRIORITY);
+      sharedCacheManager.init(conf);
+      sharedCacheManager.start();
+    } catch (Throwable t) {
+      LOG.fatal("Error starting SharedCacheManager", t);
+      System.exit(-1);
+    }
+  }
+}

hadoop-yarn-project/hadoop-yarn/hadoop-yarn-server/hadoop-yarn-server-sharedcachemanager/src/test/java/org/apache/hadoop/yarn/server/sharedcachemanager/TestRemoteAppChecker.java

@@ -0,0 +1,107 @@
+/**
+ * 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.yarn.server.sharedcachemanager;
+
+import static org.junit.Assert.assertFalse;
+import static org.junit.Assert.assertTrue;
+import static org.mockito.Mockito.doReturn;
+import static org.mockito.Mockito.doThrow;
+import static org.mockito.Mockito.spy;
+
+import org.apache.hadoop.conf.Configuration;
+import org.apache.hadoop.yarn.api.records.ApplicationId;
+import org.apache.hadoop.yarn.api.records.ApplicationReport;
+import org.apache.hadoop.yarn.api.records.YarnApplicationState;
+import org.apache.hadoop.yarn.api.records.impl.pb.ApplicationReportPBImpl;
+import org.apache.hadoop.yarn.client.api.YarnClient;
+import org.apache.hadoop.yarn.client.api.impl.YarnClientImpl;
+import org.apache.hadoop.yarn.exceptions.ApplicationNotFoundException;
+import org.junit.After;
+import org.junit.Test;
+
+public class TestRemoteAppChecker {
+
+  private RemoteAppChecker checker;
+
+  @After
+  public void cleanup() {
+    if (checker != null) {
+      checker.stop();
+    }
+  }
+
+  /**
+   * Creates/initializes/starts a RemoteAppChecker with a spied
+   * DummyYarnClientImpl.
+   * 
+   * @return the spied DummyYarnClientImpl in the created AppChecker
+   */
+  private YarnClient createCheckerWithMockedClient() {
+    YarnClient client = spy(new DummyYarnClientImpl());
+    checker = new RemoteAppChecker(client);
+    checker.init(new Configuration());
+    checker.start();
+    return client;
+  }
+
+  @Test
+  public void testNonExistentApp() throws Exception {
+    YarnClient client = createCheckerWithMockedClient();
+    ApplicationId id = ApplicationId.newInstance(1, 1);
+
+    // test for null
+    doReturn(null).when(client).getApplicationReport(id);
+    assertFalse(checker.isApplicationActive(id));
+
+    // test for ApplicationNotFoundException
+    doThrow(new ApplicationNotFoundException("Throw!")).when(client)
+        .getApplicationReport(id);
+    assertFalse(checker.isApplicationActive(id));
+  }
+
+  @Test
+  public void testRunningApp() throws Exception {
+    YarnClient client = createCheckerWithMockedClient();
+    ApplicationId id = ApplicationId.newInstance(1, 1);
+
+    // create a report and set the state to an active one
+    ApplicationReport report = new ApplicationReportPBImpl();
+    report.setYarnApplicationState(YarnApplicationState.ACCEPTED);
+    doReturn(report).when(client).getApplicationReport(id);
+
+    assertTrue(checker.isApplicationActive(id));
+  }
+
+  class DummyYarnClientImpl extends YarnClientImpl {
+    @Override
+    protected void serviceInit(Configuration conf) throws Exception {
+      // do nothing
+    }
+
+    @Override
+    protected void serviceStart() {
+      // do nothing
+    }
+
+    @Override
+    protected void serviceStop() {
+      // do nothing
+    }
+  }
+}

hadoop-yarn-project/hadoop-yarn/hadoop-yarn-server/pom.xml

@@ -39,6 +39,7 @@
     <module>hadoop-yarn-server-nodemanager</module>
     <module>hadoop-yarn-server-web-proxy</module>
     <module>hadoop-yarn-server-resourcemanager</module>
+    <module>hadoop-yarn-server-sharedcachemanager</module>
     <module>hadoop-yarn-server-tests</module>
     <module>hadoop-yarn-server-applicationhistoryservice</module>
   </modules>