YARN-10829. Support getApplications API in FederationClientInterceptor

hadoop-yarn-project/hadoop-yarn/hadoop-yarn-api/src/main/java/org/apache/hadoop/yarn/api/protocolrecords/GetApplicationsResponse.java

@@ -18,6 +18,8 @@
 
 package org.apache.hadoop.yarn.api.protocolrecords;
 
+import java.util.ArrayList;
+import java.util.Collection;
 import java.util.List;
 
 import org.apache.hadoop.classification.InterfaceAudience.Private;
@@ -52,6 +54,16 @@ public static GetApplicationsResponse newInstance(
     return response;
   }
 
+  @Private
+  @Unstable
+  public static GetApplicationsResponse newInstance(
+      Collection<ApplicationReport> applications) {
+    GetApplicationsResponse response =
+        Records.newRecord(GetApplicationsResponse.class);
+    response.setApplicationList(new ArrayList<>(applications));
+    return response;
+  }
+
   /**
    * Get <code>ApplicationReport</code> for applications.
    * @return <code>ApplicationReport</code> for applications

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

@@ -3991,6 +3991,15 @@ public static boolean isAclEnabled(Configuration conf) {
       ROUTER_PREFIX + "submit.retry";
   public static final int DEFAULT_ROUTER_CLIENTRM_SUBMIT_RETRY = 3;
 
+  /**
+   * The interceptor class used in FederationClientInterceptor should return
+   * partial ApplicationReports.
+   */
+  public static final String ROUTER_CLIENTRM_PARTIAL_RESULTS_ENABLED =
+          ROUTER_PREFIX + "partial-result.enabled";
+  public static final boolean DEFAULT_ROUTER_CLIENTRM_PARTIAL_RESULTS_ENABLED =
+          false;
+
   public static final String ROUTER_WEBAPP_PREFIX = ROUTER_PREFIX + "webapp.";
 
   public static final String ROUTER_USER_CLIENT_THREADS_SIZE =

hadoop-yarn-project/hadoop-yarn/hadoop-yarn-api/src/test/java/org/apache/hadoop/yarn/conf/TestYarnConfigurationFields.java

@@ -184,6 +184,8 @@ public void initializeMemberVariables() {
 
     configurationPrefixToSkipCompare
         .add(YarnConfiguration.ROUTER_CLIENTRM_SUBMIT_RETRY);
+    configurationPrefixToSkipCompare
+        .add(YarnConfiguration.ROUTER_CLIENTRM_PARTIAL_RESULTS_ENABLED);
     configurationPrefixToSkipCompare
         .add(YarnConfiguration.ROUTER_WEBAPP_PARTIAL_RESULTS_ENABLED);
     configurationPrefixToSkipCompare

hadoop-yarn-project/hadoop-yarn/hadoop-yarn-server/hadoop-yarn-server-router/src/main/java/org/apache/hadoop/yarn/server/router/clientrm/FederationClientInterceptor.java

@@ -22,6 +22,7 @@
 import java.io.IOException;
 import java.lang.reflect.Method;
 import java.util.ArrayList;
+import java.util.Collection;
 import java.util.List;
 import java.util.Map;
 import java.util.Random;
@@ -161,6 +162,7 @@ public class FederationClientInterceptor
   private RouterMetrics routerMetrics;
   private ThreadPoolExecutor executorService;
   private final Clock clock = new MonotonicClock();
+  private boolean returnPartialReport;
 
   @Override
   public void init(String userName) {
@@ -196,6 +198,10 @@ public void init(String userName) {
     clientRMProxies =
         new ConcurrentHashMap<SubClusterId, ApplicationClientProtocol>();
     routerMetrics = RouterMetrics.getMetrics();
+
+    returnPartialReport = conf.getBoolean(
+        YarnConfiguration.ROUTER_CLIENTRM_PARTIAL_RESULTS_ENABLED,
+        YarnConfiguration.DEFAULT_ROUTER_CLIENTRM_PARTIAL_RESULTS_ENABLED);
   }
 
   @Override
@@ -599,10 +605,44 @@ public GetApplicationReportResponse getApplicationReport(
     return response;
   }
 
+  /**
+   * The Yarn Router will forward the request to all the Yarn RMs in parallel,
+   * after that it will group all the ApplicationReports by the ApplicationId.
+   *
+   * Possible failure:
+   *
+   * Client: identical behavior as {@code ClientRMService}.
+   *
+   * Router: the Client will timeout and resubmit the request.
+   *
+   * ResourceManager: the Router calls each Yarn RM in parallel. In case a
+   * Yarn RM fails, a single call will timeout. However the Router will
+   * merge the ApplicationReports it got, and provides a partial list to
+   * the client.
+   *
+   * State Store: the Router will timeout and it will retry depending on the
+   * FederationFacade settings - if the failure happened before the select
+   * operation.
+   */
   @Override
   public GetApplicationsResponse getApplications(GetApplicationsRequest request)
       throws YarnException, IOException {
-    throw new NotImplementedException("Code is not implemented");
+    if (request == null) {
+      RouterServerUtil.logAndThrowException(
+          "Missing getApplications request.",
+          null);
+    }
+    Map<SubClusterId, SubClusterInfo> subclusters =
+        federationFacade.getSubClusters(true);
+    ClientMethod remoteMethod = new ClientMethod("getApplications",
+        new Class[] {GetApplicationsRequest.class}, new Object[] {request});
+    Map<SubClusterId, GetApplicationsResponse> applications =
+        invokeConcurrent(subclusters.keySet(), remoteMethod,
+            GetApplicationsResponse.class);
+
+    // Merge the Application Reports
+    return RouterYarnClientUtils.mergeApplications(applications.values(),
+        returnPartialReport);
   }
 
   @Override
@@ -676,6 +716,12 @@ public Object call() throws Exception {
     return results;
   }
 
+  <R> Map<SubClusterId, R> invokeConcurrent(Collection<SubClusterId> clusterIds,
+      ClientMethod request, Class<R> clazz) throws YarnException, IOException {
+    ArrayList<SubClusterId> clusterIdList = new ArrayList<>(clusterIds);
+    return invokeConcurrent(clusterIdList, request, clazz);
+  }
+
   @Override
   public GetClusterNodesResponse getClusterNodes(GetClusterNodesRequest request)
       throws YarnException, IOException {

hadoop-yarn-project/hadoop-yarn/hadoop-yarn-server/hadoop-yarn-server-router/src/main/java/org/apache/hadoop/yarn/server/router/clientrm/RouterYarnClientUtils.java

@@ -18,14 +18,25 @@
 package org.apache.hadoop.yarn.server.router.clientrm;
 
 import java.util.Collection;
+import java.util.HashMap;
+import java.util.Map;
+
+import org.apache.hadoop.yarn.api.protocolrecords.GetApplicationsResponse;
 import org.apache.hadoop.yarn.api.protocolrecords.GetClusterMetricsResponse;
+import org.apache.hadoop.yarn.api.records.ApplicationId;
+import org.apache.hadoop.yarn.api.records.ApplicationReport;
+import org.apache.hadoop.yarn.api.records.ApplicationResourceUsageReport;
 import org.apache.hadoop.yarn.api.records.YarnClusterMetrics;
+import org.apache.hadoop.yarn.server.uam.UnmanagedApplicationManager;
+import org.apache.hadoop.yarn.util.resource.Resources;
 
 /**
  * Util class for Router Yarn client API calls.
  */
 public final class RouterYarnClientUtils {
 
+  private final static String PARTIAL_REPORT = "Partial Report ";
+
   private RouterYarnClientUtils() {
 
   }
@@ -52,4 +63,130 @@ public static GetClusterMetricsResponse merge(
     }
     return GetClusterMetricsResponse.newInstance(tmp);
   }
+
+  /**
+   * Merges a list of ApplicationReports grouping by ApplicationId.
+   * Our current policy is to merge the application reports from the reachable
+   * SubClusters.
+   * @param responses a list of ApplicationResponse to merge
+   * @param returnPartialResult if the merge ApplicationReports should contain
+   * partial result or not
+   * @return the merged ApplicationsResponse
+   */
+  public static GetApplicationsResponse mergeApplications(
+      Collection<GetApplicationsResponse> responses,
+      boolean returnPartialResult){
+    Map<ApplicationId, ApplicationReport> federationAM = new HashMap<>();
+    Map<ApplicationId, ApplicationReport> federationUAMSum = new HashMap<>();
+
+    for (GetApplicationsResponse appResponse : responses){
+      for (ApplicationReport appReport : appResponse.getApplicationList()){
+        ApplicationId appId = appReport.getApplicationId();
+        // Check if this ApplicationReport is an AM
+        if (!appReport.isUnmanagedApp()) {
+          // Insert in the list of AM
+          federationAM.put(appId, appReport);
+          // Check if there are any UAM found before
+          if (federationUAMSum.containsKey(appId)) {
+            // Merge the current AM with the found UAM
+            mergeAMWithUAM(appReport, federationUAMSum.get(appId));
+            // Remove the sum of the UAMs
+            federationUAMSum.remove(appId);
+          }
+          // This ApplicationReport is an UAM
+        } else if (federationAM.containsKey(appId)) {
+          // Merge the current UAM with its own AM
+          mergeAMWithUAM(federationAM.get(appId), appReport);
+        } else if (federationUAMSum.containsKey(appId)) {
+          // Merge the current UAM with its own UAM and update the list of UAM
+          ApplicationReport mergedUAMReport =
+              mergeUAMWithUAM(federationUAMSum.get(appId), appReport);
+          federationUAMSum.put(appId, mergedUAMReport);
+        } else {
+          // Insert in the list of UAM
+          federationUAMSum.put(appId, appReport);
+        }
+      }
+    }
+    // Check the remaining UAMs are depending or not from federation
+    for (ApplicationReport appReport : federationUAMSum.values()) {
+      if (mergeUamToReport(appReport.getName(), returnPartialResult)) {
+        federationAM.put(appReport.getApplicationId(), appReport);
+      }
+    }
+
+    return GetApplicationsResponse.newInstance(federationAM.values());
+  }
+
+  private static ApplicationReport mergeUAMWithUAM(ApplicationReport uam1,
+      ApplicationReport uam2){
+    uam1.setName(PARTIAL_REPORT + uam1.getApplicationId());
+    mergeAMWithUAM(uam1, uam2);
+    return uam1;
+  }
+
+  private static void mergeAMWithUAM(ApplicationReport am,
+      ApplicationReport uam){
+    ApplicationResourceUsageReport amResourceReport =
+        am.getApplicationResourceUsageReport();
+
+    ApplicationResourceUsageReport uamResourceReport =
+        uam.getApplicationResourceUsageReport();
+
+    amResourceReport.setNumUsedContainers(
+        amResourceReport.getNumUsedContainers() +
+            uamResourceReport.getNumUsedContainers());
+
+    amResourceReport.setNumReservedContainers(
+        amResourceReport.getNumReservedContainers() +
+            uamResourceReport.getNumReservedContainers());
+
+    amResourceReport.setUsedResources(Resources.add(
+        amResourceReport.getUsedResources(),
+        uamResourceReport.getUsedResources()));
+
+    amResourceReport.setReservedResources(Resources.add(
+        amResourceReport.getReservedResources(),
+        uamResourceReport.getReservedResources()));
+
+    amResourceReport.setNeededResources(Resources.add(
+        amResourceReport.getNeededResources(),
+        uamResourceReport.getNeededResources()));
+
+    amResourceReport.setMemorySeconds(
+        amResourceReport.getMemorySeconds() +
+            uamResourceReport.getMemorySeconds());
+
+    amResourceReport.setVcoreSeconds(
+        amResourceReport.getVcoreSeconds() +
+            uamResourceReport.getVcoreSeconds());
+
+    amResourceReport.setQueueUsagePercentage(
+        amResourceReport.getQueueUsagePercentage() +
+            uamResourceReport.getQueueUsagePercentage());
+
+    amResourceReport.setClusterUsagePercentage(
+        amResourceReport.getClusterUsagePercentage() +
+            uamResourceReport.getClusterUsagePercentage());
+
+    am.setApplicationResourceUsageReport(amResourceReport);
+  }
+
+  /**
+   * Returns whether or not to add an unmanaged application to the report.
+   * @param appName Application Name
+   * @param returnPartialResult if the merge ApplicationReports should contain
+   * partial result or not
+   */
+  private static boolean mergeUamToReport(String appName,
+      boolean returnPartialResult){
+    if (returnPartialResult) {
+      return true;
+    }
+    if (appName == null) {
+      return false;
+    }
+    return !(appName.startsWith(UnmanagedApplicationManager.APP_NAME) ||
+        appName.startsWith(PARTIAL_REPORT));
+  }
 }