YARN-9048. Add znode hierarchy in Federation ZK State Store. (#6016)

hadoop-yarn-project/hadoop-yarn/hadoop-yarn-server/hadoop-yarn-server-common/src/main/java/org/apache/hadoop/yarn/server/federation/store/impl/ZookeeperFederationStateStore.java

@@ -26,6 +26,8 @@ import java.nio.ByteBuffer;
 import java.util.ArrayList;
 import java.util.Calendar;
 import java.util.List;
+import java.util.Map;
+import java.util.HashMap;
 import java.util.TimeZone;
 import java.util.Comparator;
 import java.util.stream.Collectors;
@@ -111,6 +113,7 @@ import org.apache.hadoop.yarn.server.records.impl.pb.VersionPBImpl;
 import org.apache.hadoop.yarn.util.Clock;
 import org.apache.hadoop.yarn.util.Records;
 import org.apache.hadoop.yarn.util.SystemClock;
+import org.apache.zookeeper.KeeperException;
 import org.apache.zookeeper.data.ACL;
 import org.slf4j.Logger;
 import org.slf4j.LoggerFactory;
@@ -131,8 +134,16 @@ import static org.apache.hadoop.util.curator.ZKCuratorManager.getNodePath;
  * |     |----- SC1
  * |     |----- SC2
  * |--- APPLICATION
- * |     |----- APP1
- * |     |----- APP2
+ * |     |----- HIERARCHIES
+ * |     |        |----- 1
+ * |     |        |      |----- (#ApplicationId barring last character)
+ * |     |        |      |       |       |----- APP Data
+ * |     |        |      ....
+ * |     |        |
+ * |     |        |----- 2
+ * |     |        |      |----- (#ApplicationId barring last 2 characters)
+ * |     |        |      |       |----- (#Last 2 characters of ApplicationId)
+ * |     |        |      |       |       |----- APP Data
  * |--- POLICY
  * |     |----- QUEUE1
  * |     |----- QUEUE1
@@ -194,12 +205,19 @@ public class ZookeeperFederationStateStore implements FederationStateStore {
   private int maxAppsInStateStore;
 
   /** Directory to store the delegation token data. **/
+  private Map<Integer, String> routerAppRootHierarchies;
   private String routerRMDTSecretManagerRoot;
   private String routerRMDTMasterKeysRootPath;
   private String routerRMDelegationTokensRootPath;
   private String routerRMSequenceNumberPath;
   private String routerRMMasterKeyIdPath;
 
+  private int appIdNodeSplitIndex = 0;
+  private final static int HIERARCHIES_LEVEL = 4;
+
+  @VisibleForTesting
+  public static final String ROUTER_APP_ROOT_HIERARCHIES = "HIERARCHIES";
+
   private volatile Clock clock = SystemClock.getInstance();
 
   protected static final Version CURRENT_VERSION_INFO = Version.newInstance(1, 1);
@@ -208,6 +226,27 @@ public class ZookeeperFederationStateStore implements FederationStateStore {
   private ZKFederationStateStoreOpDurations opDurations =
       ZKFederationStateStoreOpDurations.getInstance();
 
+  /*
+   * Indicates different app attempt state store operations.
+   */
+  private enum AppAttemptOp {
+    STORE,
+    UPDATE,
+    REMOVE
+  };
+
+  /**
+   * Encapsulates full app node path and corresponding split index.
+   */
+  private final static class AppNodeSplitInfo {
+    private final String path;
+    private final int splitIndex;
+    AppNodeSplitInfo(String path, int splitIndex) {
+      this.path = path;
+      this.splitIndex = splitIndex;
+    }
+  }
+
   @Override
   public void init(Configuration conf) throws YarnException {
 
@@ -234,6 +273,23 @@ public class ZookeeperFederationStateStore implements FederationStateStore {
     reservationsZNode = getNodePath(baseZNode, ROOT_ZNODE_NAME_RESERVATION);
     versionNode = getNodePath(baseZNode, ROOT_ZNODE_NAME_VERSION);
 
+    String hierarchiesPath = getNodePath(appsZNode, ROUTER_APP_ROOT_HIERARCHIES);
+    routerAppRootHierarchies = new HashMap<>();
+    routerAppRootHierarchies.put(0, appsZNode);
+    for (int splitIndex = 1; splitIndex <= HIERARCHIES_LEVEL; splitIndex++) {
+      routerAppRootHierarchies.put(splitIndex,
+          getNodePath(hierarchiesPath, Integer.toString(splitIndex)));
+    }
+
+    appIdNodeSplitIndex = conf.getInt(YarnConfiguration.ZK_APPID_NODE_SPLIT_INDEX,
+         YarnConfiguration.DEFAULT_ZK_APPID_NODE_SPLIT_INDEX);
+    if (appIdNodeSplitIndex < 1 || appIdNodeSplitIndex > HIERARCHIES_LEVEL) {
+      LOG.info("Invalid value {} for config {} specified. Resetting it to {}",
+          appIdNodeSplitIndex, YarnConfiguration.ZK_APPID_NODE_SPLIT_INDEX,
+          YarnConfiguration.DEFAULT_ZK_APPID_NODE_SPLIT_INDEX);
+      appIdNodeSplitIndex = YarnConfiguration.DEFAULT_ZK_APPID_NODE_SPLIT_INDEX;
+    }
+
     // delegation token znodes
     routerRMDTSecretManagerRoot = getNodePath(baseZNode, ROUTER_RM_DT_SECRET_MANAGER_ROOT);
     routerRMDTMasterKeysRootPath = getNodePath(routerRMDTSecretManagerRoot,
@@ -250,6 +306,12 @@ public class ZookeeperFederationStateStore implements FederationStateStore {
       List<ACL> zkAcl = ZKCuratorManager.getZKAcls(conf);
       zkManager.createRootDirRecursively(membershipZNode, zkAcl);
       zkManager.createRootDirRecursively(appsZNode, zkAcl);
+      zkManager.createRootDirRecursively(
+          getNodePath(appsZNode, ROUTER_APP_ROOT_HIERARCHIES));
+      for (int splitIndex = 1; splitIndex <= HIERARCHIES_LEVEL; splitIndex++) {
+        zkManager.createRootDirRecursively(
+            routerAppRootHierarchies.get(splitIndex));
+      }
       zkManager.createRootDirRecursively(policiesZNode, zkAcl);
       zkManager.createRootDirRecursively(reservationsZNode, zkAcl);
       zkManager.createRootDirRecursively(routerRMDTSecretManagerRoot, zkAcl);
@@ -320,6 +382,21 @@ public class ZookeeperFederationStateStore implements FederationStateStore {
     }
   }
 
+  /**
+   * Register the home {@code SubClusterId} of the newly submitted
+   * {@code ApplicationId}. Currently response is empty if the operation was
+   * successful, if not an exception reporting reason for a failure. If a
+   * mapping for the application already existed, the {@code SubClusterId} in
+   * this response will return the existing mapping which might be different
+   * from that in the {@code AddApplicationHomeSubClusterRequest}.
+   *
+   * @param request the request to register a new application with its home sub-cluster.
+   * @return upon successful registration of the application in the StateStore,
+   *         {@code AddApplicationHomeSubClusterRequest} containing the home
+   *         sub-cluster of the application. Otherwise, an exception reporting
+   *         reason for a failure.
+   * @throws YarnException indicates exceptions from yarn servers.
+   */
   @Override
   public AddApplicationHomeSubClusterResponse addApplicationHomeSubCluster(
       AddApplicationHomeSubClusterRequest request) throws YarnException {
@@ -367,6 +444,17 @@ public class ZookeeperFederationStateStore implements FederationStateStore {
     throw new YarnException("Cannot addApplicationHomeSubCluster by request");
   }
 
+  /**
+   * Update the home {@code SubClusterId} of a previously submitted
+   * {@code ApplicationId}. Currently response is empty if the operation was
+   * successful, if not an exception reporting reason for a failure.
+   *
+   * @param request the request to update the home sub-cluster of an
+   *          application.
+   * @return empty on successful update of the application in the StateStore, if
+   *         not an exception reporting reason for a failure
+   * @throws YarnException indicates exceptions from yarn servers.
+   */
   @Override
   public UpdateApplicationHomeSubClusterResponse updateApplicationHomeSubCluster(
       UpdateApplicationHomeSubClusterRequest request) throws YarnException {
@@ -402,6 +490,15 @@ public class ZookeeperFederationStateStore implements FederationStateStore {
     return UpdateApplicationHomeSubClusterResponse.newInstance();
   }
 
+  /**
+   * Get information about the application identified by the input
+   * {@code ApplicationId}.
+   *
+   * @param request contains the application queried
+   * @return {@code ApplicationHomeSubCluster} containing the application's home
+   *         subcluster
+   * @throws YarnException indicates exceptions from yarn servers.
+   */
   @Override
   public GetApplicationHomeSubClusterResponse getApplicationHomeSubCluster(
       GetApplicationHomeSubClusterRequest request) throws YarnException {
@@ -437,6 +534,14 @@ public class ZookeeperFederationStateStore implements FederationStateStore {
         subClusterId, createTime);
   }
 
+  /**
+   * Get the {@code ApplicationHomeSubCluster} list representing the mapping of
+   * all submitted applications to it's home sub-cluster.
+   *
+   * @param request empty representing all applications
+   * @return the mapping of all submitted application to it's home sub-cluster
+   * @throws YarnException indicates exceptions from yarn servers.
+   */
   @Override
   public GetApplicationsHomeSubClusterResponse getApplicationsHomeSubCluster(
       GetApplicationsHomeSubClusterRequest request) throws YarnException {
@@ -448,9 +553,7 @@ public class ZookeeperFederationStateStore implements FederationStateStore {
     try {
       long start = clock.getTime();
       SubClusterId requestSC = request.getSubClusterId();
-      List<String> children = zkManager.getChildren(appsZNode);
-      List<ApplicationHomeSubCluster> result = children.stream()
-          .map(child -> generateAppHomeSC(child))
+      List<ApplicationHomeSubCluster> result = loadRouterApplications().stream()
           .sorted(Comparator.comparing(ApplicationHomeSubCluster::getCreateTime).reversed())
           .filter(appHomeSC -> filterHomeSubCluster(requestSC, appHomeSC.getHomeSubCluster()))
           .limit(maxAppsInStateStore)
@@ -467,48 +570,51 @@ public class ZookeeperFederationStateStore implements FederationStateStore {
     throw new YarnException("Cannot get app by request");
   }
 
-  private ApplicationHomeSubCluster generateAppHomeSC(String appId) {
-    try {
-      // Parse ApplicationHomeSubCluster
-      ApplicationId applicationId = ApplicationId.fromString(appId);
-      ApplicationHomeSubCluster zkStoreApplicationHomeSubCluster =
-          getApplicationHomeSubCluster(applicationId);
-
-      // Prepare to return data
-      SubClusterId subClusterId = zkStoreApplicationHomeSubCluster.getHomeSubCluster();
-      ApplicationHomeSubCluster resultApplicationHomeSubCluster =
-          ApplicationHomeSubCluster.newInstance(applicationId, subClusterId);
-      return resultApplicationHomeSubCluster;
-    } catch (Exception ex) {
-      LOG.error("get homeSubCluster by appId = {}.", appId, ex);
-    }
-    return null;
-  }
-
+  /**
+   * Delete the mapping of home {@code SubClusterId} of a previously submitted
+   * {@code ApplicationId}. Currently response is empty if the operation was
+   * successful, if not an exception reporting reason for a failure.
+   *
+   * @param request the request to delete the home sub-cluster of an
+   *          application.
+   * @return empty on successful update of the application in the StateStore, if
+   *         not an exception reporting reason for a failure
+   * @throws YarnException if the request is invalid/fails
+   */
   @Override
-  public DeleteApplicationHomeSubClusterResponse
-      deleteApplicationHomeSubCluster(
-          DeleteApplicationHomeSubClusterRequest request)
-              throws YarnException {
+  public DeleteApplicationHomeSubClusterResponse deleteApplicationHomeSubCluster(
+      DeleteApplicationHomeSubClusterRequest request) throws YarnException {
     long start = clock.getTime();
     FederationApplicationHomeSubClusterStoreInputValidator.validate(request);
     ApplicationId appId = request.getApplicationId();
-    String appZNode = getNodePath(appsZNode, appId.toString());
+    String appIdRemovePath = getLeafAppIdNodePath(appId.toString(), false);
+    int splitIndex = appIdNodeSplitIndex;
 
-    boolean exists = false;
+    boolean exists = true;
     try {
-      exists = zkManager.exists(appZNode);
+      if (!exists(appIdRemovePath)) {
+        AppNodeSplitInfo alternatePathInfo = getAlternatePath(appId.toString());
+        if (alternatePathInfo != null) {
+          appIdRemovePath = alternatePathInfo.path;
+          splitIndex = alternatePathInfo.splitIndex;
+        } else {
+          exists = false;
+        }
+      }
     } catch (Exception e) {
       String errMsg = "Cannot check app: " + e.getMessage();
       FederationStateStoreUtils.logAndThrowStoreException(LOG, errMsg);
     }
+
     if (!exists) {
       String errMsg = "Application " + appId + " does not exist";
       FederationStateStoreUtils.logAndThrowStoreException(LOG, errMsg);
     }
 
     try {
-      zkManager.delete(appZNode);
+      zkManager.delete(appIdRemovePath);
+      // Check if we should remove the parent app node as well.
+      checkRemoveParentAppNode(appIdRemovePath, splitIndex);
     } catch (Exception e) {
       String errMsg = "Cannot delete app: " + e.getMessage();
       FederationStateStoreUtils.logAndThrowStoreException(LOG, errMsg);
@@ -730,11 +836,12 @@ public class ZookeeperFederationStateStore implements FederationStateStore {
    *
    * @param appId Application identifier.
    * @return ApplicationHomeSubCluster identifier.
-   * @throws Exception If it cannot contact ZooKeeper.
+   * @throws YarnException If it cannot contact ZooKeeper.
    */
   private ApplicationHomeSubCluster getApplicationHomeSubCluster(
-      final ApplicationId appId) throws YarnException {
-    String appZNode = getNodePath(appsZNode, appId.toString());
+      final ApplicationId appId) throws YarnException{
+
+    String appZNode = getLeafAppIdNodePath(appId.toString(), false);
 
     ApplicationHomeSubCluster appHomeSubCluster = null;
     byte[] data = get(appZNode);
@@ -761,11 +868,44 @@ public class ZookeeperFederationStateStore implements FederationStateStore {
   private void storeOrUpdateApplicationHomeSubCluster(final ApplicationId applicationId,
       final ApplicationHomeSubCluster applicationHomeSubCluster, boolean update)
       throws YarnException {
-    String appZNode = getNodePath(appsZNode, applicationId.toString());
-    ApplicationHomeSubClusterProto proto =
-        ((ApplicationHomeSubClusterPBImpl) applicationHomeSubCluster).getProto();
-    byte[] data = proto.toByteArray();
-    put(appZNode, data, update);
+    try {
+      ApplicationHomeSubClusterProto proto =
+          ((ApplicationHomeSubClusterPBImpl) applicationHomeSubCluster).getProto();
+      byte[] data = proto.toByteArray();
+      if (update) {
+        updateApplicationStateInternal(applicationId, data);
+      } else {
+        storeApplicationStateInternal(applicationId, data);
+      }
+    } catch (Exception e) {
+      throw new YarnException(e);
+    }
+  }
+
+  protected void storeApplicationStateInternal(final ApplicationId applicationId, byte[] data)
+      throws Exception {
+    String nodeCreatePath = getLeafAppIdNodePath(applicationId.toString(), true);
+    LOG.debug("Storing info for app: {} at: {}.", applicationId, nodeCreatePath);
+    put(nodeCreatePath, data, false);
+  }
+
+  protected void updateApplicationStateInternal(final ApplicationId applicationId, byte[] data)
+      throws Exception {
+    String nodeUpdatePath = getLeafAppIdNodePath(applicationId.toString(), false);
+    if (!exists(nodeUpdatePath)) {
+      AppNodeSplitInfo alternatePathInfo = getAlternatePath(applicationId.toString());
+      if (alternatePathInfo != null) {
+        nodeUpdatePath = alternatePathInfo.path;
+      } else if (appIdNodeSplitIndex != 0) {
+        // No alternate path exists. Create path as per configured split index.
+        String rootNode = getSplitAppNodeParent(nodeUpdatePath, appIdNodeSplitIndex);
+        if (!exists(rootNode)) {
+          zkManager.create(rootNode);
+        }
+      }
+    }
+    LOG.debug("Storing final state info for app: {} at: {}.", applicationId, nodeUpdatePath);
+    put(nodeUpdatePath, data, true);
   }
 
   /**
@@ -1674,4 +1814,198 @@ public class ZookeeperFederationStateStore implements FederationStateStore {
     }
     return keyIdSeqCounter.getCount();
   }
+
+  /**
+   * Get parent app node path based on full path and split index supplied.
+   * @param appIdPath App id path for which parent needs to be returned.
+   * @param splitIndex split index.
+   * @return parent app node path.
+   */
+  private String getSplitAppNodeParent(String appIdPath, int splitIndex) {
+    // Calculated as string upto index (appIdPath Length - split index - 1). We
+    // deduct 1 to exclude path separator.
+    return appIdPath.substring(0, appIdPath.length() - splitIndex - 1);
+  }
+
+  /**
+   * Checks if parent app node has no leaf nodes and if it does not have,
+   * removes it. Called while removing application.
+   *
+   * @param appIdPath path of app id to be removed.
+   * @param splitIndex split index.
+   * @throws Exception if any problem occurs while performing ZK operation.
+   */
+  private void checkRemoveParentAppNode(String appIdPath, int splitIndex)
+      throws Exception {
+    if (splitIndex == 0) {
+      return;
+    }
+
+    String parentAppNode = getSplitAppNodeParent(appIdPath, splitIndex);
+    List<String> children;
+    try {
+      children = getChildren(parentAppNode);
+    } catch (KeeperException.NoNodeException ke) {
+      // It should be fine to swallow this exception as the parent app node we
+      // intend to delete is already deleted.
+      LOG.debug("Unable to remove app parent node {} as it does not exist.",
+          parentAppNode);
+      return;
+    }
+
+    // If children==null or children is not empty, we cannot delete the parent path.
+    if (children == null || !children.isEmpty()) {
+      return;
+    }
+
+    // No apps stored under parent path.
+    try {
+      zkManager.delete(parentAppNode);
+      LOG.debug("No leaf app node exists. Removing parent node {}.", parentAppNode);
+    } catch (KeeperException.NotEmptyException ke) {
+      // It should be fine to swallow this exception as the parent app node
+      // has to be deleted only if it has no children. And this node has.
+      LOG.debug("Unable to remove app parent node {} as it has children.",
+          parentAppNode);
+    }
+  }
+
+  List<String> getChildren(final String path) throws Exception {
+    return zkManager.getChildren(path);
+  }
+
+  /**
+   * Get alternate path for app id if path according to configured split index
+   * does not exist. We look for path based on all possible split indices.
+   * @param appId
+   * @return a {@link AppNodeSplitInfo} object containing the path and split
+   *    index if it exists, null otherwise.
+   * @throws Exception if any problem occurs while performing ZK operation.
+   */
+  private AppNodeSplitInfo getAlternatePath(String appId) throws Exception {
+    for (Map.Entry<Integer, String> entry : routerAppRootHierarchies.entrySet()) {
+      // Look for other paths
+      int splitIndex = entry.getKey();
+      if (splitIndex != appIdNodeSplitIndex) {
+        String alternatePath =
+            getLeafAppIdNodePath(appId, entry.getValue(), splitIndex, false);
+        if (exists(alternatePath)) {
+          return new AppNodeSplitInfo(alternatePath, splitIndex);
+        }
+      }
+    }
+    return null;
+  }
+
+  /**
+   * Returns leaf app node path based on app id and passed split index. If the
+   * passed flag createParentIfNotExists is true, also creates the parent app
+   * node if it does not exist.
+   * @param appId application id.
+   * @param rootNode app root node based on split index.
+   * @param appIdNodeSplitIdx split index.
+   * @param createParentIfNotExists flag which determines if parent app node
+   *     needs to be created(as per split) if it does not exist.
+   * @return leaf app node path.
+   * @throws Exception if any problem occurs while performing ZK operation.
+   */
+  private String getLeafAppIdNodePath(String appId, String rootNode,
+       int appIdNodeSplitIdx, boolean createParentIfNotExists) throws Exception {
+    if (appIdNodeSplitIdx == 0) {
+      return getNodePath(rootNode, appId);
+    }
+    String nodeName = appId;
+    int splitIdx = nodeName.length() - appIdNodeSplitIdx;
+    String rootNodePath = getNodePath(rootNode, nodeName.substring(0, splitIdx));
+    if (createParentIfNotExists && !exists(rootNodePath)) {
+      try {
+        zkManager.create(rootNodePath);
+      } catch (KeeperException.NodeExistsException e) {
+        LOG.debug("Unable to create app parent node {} as it already exists.", rootNodePath);
+      }
+    }
+    return getNodePath(rootNodePath, nodeName.substring(splitIdx));
+  }
+
+  /**
+   * Returns leaf app node path based on app id and configured split index. If
+   * the passed flag createParentIfNotExists is true, also creates the parent
+   * app node if it does not exist.
+   * @param appId application id.
+   * @param createParentIfNotExists flag which determines if parent app node
+   *     needs to be created(as per split) if it does not exist.
+   * @return leaf app node path.
+   * @throws YarnException if any problem occurs while performing ZK operation.
+   */
+  private String getLeafAppIdNodePath(String appId,
+      boolean createParentIfNotExists) throws YarnException {
+    try {
+      String rootNode = routerAppRootHierarchies.get(appIdNodeSplitIndex);
+      return getLeafAppIdNodePath(appId, rootNode, appIdNodeSplitIndex, createParentIfNotExists);
+    } catch (Exception e) {
+      throw new YarnException(e);
+    }
+  }
+
+  private ApplicationHomeSubCluster loadRouterAppStateFromAppNode(String appNodePath)
+      throws Exception {
+    byte[] data = get(appNodePath);
+    LOG.debug("Loading application from znode: {}", appNodePath);
+    ApplicationHomeSubCluster appHomeSubCluster = null;
+
+    if (data == null) {
+      return appHomeSubCluster;
+    }
+
+    try {
+      appHomeSubCluster = new ApplicationHomeSubClusterPBImpl(
+          ApplicationHomeSubClusterProto.parseFrom(data));
+    } catch (InvalidProtocolBufferException e) {
+      String errMsg = "Cannot parse application at " + appNodePath;
+      FederationStateStoreUtils.logAndThrowStoreException(LOG, errMsg);
+    }
+
+    return appHomeSubCluster;
+  }
+
+  private List<ApplicationHomeSubCluster> loadRouterApplications() throws Exception {
+    List<ApplicationHomeSubCluster> applicationHomeSubClusters = new ArrayList<>();
+    for (int splitIndex = 0; splitIndex <= 4; splitIndex++) {
+      String appRoot = routerAppRootHierarchies.get(splitIndex);
+      if (appRoot == null) {
+        continue;
+      }
+      List<String> childNodes = getChildren(appRoot);
+      boolean appNodeFound = false;
+      for (String childNodeName : childNodes) {
+        if (childNodeName.startsWith(ApplicationId.appIdStrPrefix)) {
+          appNodeFound = true;
+          if (splitIndex == 0) {
+            ApplicationHomeSubCluster applicationHomeSubCluster =
+                    loadRouterAppStateFromAppNode(getNodePath(appRoot, childNodeName));
+            applicationHomeSubClusters.add(applicationHomeSubCluster);
+          } else {
+            // If AppId Node is partitioned.
+            String parentNodePath = getNodePath(appRoot, childNodeName);
+            List<String> leafNodes = getChildren(parentNodePath);
+            for (String leafNodeName : leafNodes) {
+              ApplicationHomeSubCluster applicationHomeSubCluster =
+                      loadRouterAppStateFromAppNode(getNodePath(parentNodePath, leafNodeName));
+              applicationHomeSubClusters.add(applicationHomeSubCluster);
+            }
+          }
+        } else if (!childNodeName.equals(ROUTER_APP_ROOT_HIERARCHIES)){
+          LOG.debug("Unknown child node with name {} under {}.", childNodeName, appRoot);
+        }
+      }
+      if (splitIndex != appIdNodeSplitIndex && !appNodeFound) {
+        // If no loaded app exists for a particular split index and the split
+        // index for which apps are being loaded is not the one configured, then
+        // we do not need to keep track of this hierarchy for storing/updating/
+        // removing app/app attempt znodes.
+        routerAppRootHierarchies.remove(splitIndex);
+      }
+    }
+    return applicationHomeSubClusters;
+  }
 }

hadoop-yarn-project/hadoop-yarn/hadoop-yarn-server/hadoop-yarn-server-common/src/test/resources/yarn-site.xml

@@ -0,0 +1,22 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<?xml-stylesheet type="text/xsl" href="configuration.xsl"?>
+<!--
+  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.
+-->
+
+<configuration>
+  <property>
+    <name>yarn.resourcemanager.zk-appid-node.split-index</name>
+    <value>1</value>
+  </property>
+</configuration>