YARN-3222. Fixed NPE on RMNodeImpl#ReconnectNodeTransition when a node is reconnected with a different port. Contributed by Rohith Sharmaks

(cherry picked from commit b2f1ec312e)

hadoop-yarn-project/hadoop-yarn/hadoop-yarn-server/hadoop-yarn-server-resourcemanager/src/main/java/org/apache/hadoop/yarn/server/resourcemanager/rmnode/RMNodeImpl.java

@@ -575,8 +575,8 @@ public class RMNodeImpl implements RMNode, EventHandler<RMNodeEvent> {
         if (rmNode.getHttpPort() == newNode.getHttpPort()) {
           // Reset heartbeat ID since node just restarted.
           rmNode.getLastNodeHeartBeatResponse().setResponseId(0);
-          if (rmNode.getState() != NodeState.UNHEALTHY) {
+          if (rmNode.getState().equals(NodeState.RUNNING)) {
-            // Only add new node if old state is not UNHEALTHY
+            // Only add new node if old state is RUNNING
             rmNode.context.getDispatcher().getEventHandler().handle(
                 new NodeAddedSchedulerEvent(newNode));
           }
@@ -599,30 +599,32 @@ public class RMNodeImpl implements RMNode, EventHandler<RMNodeEvent> {
       } else {
         rmNode.httpPort = newNode.getHttpPort();
         rmNode.httpAddress = newNode.getHttpAddress();
+        boolean isCapabilityChanged = false;
+        if (rmNode.getTotalCapability() != newNode.getTotalCapability()) {
           rmNode.totalCapability = newNode.getTotalCapability();
+          isCapabilityChanged = true;
+        }
       
         handleNMContainerStatus(reconnectEvent.getNMContainerStatuses(), rmNode);
 
         // Reset heartbeat ID since node just restarted.
         rmNode.getLastNodeHeartBeatResponse().setResponseId(0);
-      }
 
-      if (null != reconnectEvent.getRunningApplications()) {
         for (ApplicationId appId : reconnectEvent.getRunningApplications()) {
           handleRunningAppOnNode(rmNode, rmNode.context, appId, rmNode.nodeId);
         }
-      }
 
-      rmNode.context.getDispatcher().getEventHandler().handle(
+        if (isCapabilityChanged
-          new NodesListManagerEvent(
+            && rmNode.getState().equals(NodeState.RUNNING)) {
-              NodesListManagerEventType.NODE_USABLE, rmNode));
-      if (rmNode.getState().equals(NodeState.RUNNING)) {
           // Update scheduler node's capacity for reconnect node.
-        rmNode.context.getDispatcher().getEventHandler().handle(
+          rmNode.context
-            new NodeResourceUpdateSchedulerEvent(rmNode, 
+              .getDispatcher()
-                ResourceOption.newInstance(newNode.getTotalCapability(), -1)));
+              .getEventHandler()
+              .handle(
+                  new NodeResourceUpdateSchedulerEvent(rmNode, ResourceOption
+                      .newInstance(newNode.getTotalCapability(), -1)));
+        }
       }
-      
     }
 
     private void handleNMContainerStatus(

hadoop-yarn-project/hadoop-yarn/hadoop-yarn-server/hadoop-yarn-server-resourcemanager/src/test/java/org/apache/hadoop/yarn/server/resourcemanager/MockNM.java

@@ -51,7 +51,7 @@ public class MockNM {
   private final int memory;
   private final int vCores;
   private ResourceTrackerService resourceTracker;
-  private final int httpPort = 2;
+  private int httpPort = 2;
   private MasterKey currentContainerTokenMasterKey;
   private MasterKey currentNMTokenMasterKey;
   private String version;
@@ -87,6 +87,10 @@ public class MockNM {
     return httpPort;
   }
   
+  public void setHttpPort(int port) {
+    httpPort = port;
+  }
+
   public void setResourceTrackerService(ResourceTrackerService resourceTracker) {
     this.resourceTracker = resourceTracker;
   }

hadoop-yarn-project/hadoop-yarn/hadoop-yarn-server/hadoop-yarn-server-resourcemanager/src/test/java/org/apache/hadoop/yarn/server/resourcemanager/TestResourceTrackerService.java

@@ -56,6 +56,7 @@ import org.apache.hadoop.yarn.server.api.protocolrecords.RegisterNodeManagerResp
 import org.apache.hadoop.yarn.server.api.records.NodeAction;
 import org.apache.hadoop.yarn.server.resourcemanager.rmapp.RMApp;
 import org.apache.hadoop.yarn.server.resourcemanager.rmapp.attempt.RMAppAttemptImpl;
+import org.apache.hadoop.yarn.server.resourcemanager.rmnode.RMNode;
 import org.apache.hadoop.yarn.server.resourcemanager.scheduler.QueueMetrics;
 import org.apache.hadoop.yarn.server.resourcemanager.scheduler.event.SchedulerEvent;
 import org.apache.hadoop.yarn.server.utils.BuilderUtils;
@@ -633,6 +634,20 @@ public class TestResourceTrackerService {
     dispatcher.await();
     Assert.assertTrue(NodeAction.NORMAL.equals(response.getNodeAction()));
     Assert.assertEquals(5120 + 15360, metrics.getAvailableMB());
+    
+    // reconnect healthy node changing http port
+    nm1 = new MockNM("host1:1234", 5120, rm.getResourceTrackerService());
+    nm1.setHttpPort(3);
+    nm1.registerNode();
+    dispatcher.await();
+    response = nm1.nodeHeartbeat(true);
+    response = nm1.nodeHeartbeat(true);
+    dispatcher.await();
+    RMNode rmNode = rm.getRMContext().getRMNodes().get(nm1.getNodeId());
+    Assert.assertEquals(3, rmNode.getHttpPort());
+    Assert.assertEquals(5120, rmNode.getTotalCapability().getMemory());
+    Assert.assertEquals(5120 + 15360, metrics.getAvailableMB());
+
   }
 
   private void writeToHostsFile(String... hosts) throws IOException {