YARN-5544. TestNodeBlacklistingOnAMFailures fails on trunk. Contributed by Sunil G.

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

@@ -68,6 +68,9 @@ public class TestNodeBlacklistingOnAMFailures {
     MockRM rm = startRM(conf, dispatcher);
     CapacityScheduler scheduler = (CapacityScheduler) rm.getResourceScheduler();
 
+    // Register 5 nodes, so that we can blacklist atleast one if AM container
+    // is failed. As per calculation it will be like, 5nodes * 0.2 (default)=1.
+    // First register 2 nodes, and after AM lauched register 3 more nodes.
     MockNM nm1 =
         new MockNM("127.0.0.1:1234", 8000, rm.getResourceTrackerService());
     nm1.registerNode();
@@ -93,6 +96,19 @@ public class TestNodeBlacklistingOnAMFailures {
       otherNode = nm1;
     }
 
+    // register 3 nodes now
+    MockNM nm3 =
+        new MockNM("127.0.0.3:2345", 8000, rm.getResourceTrackerService());
+    nm3.registerNode();
+
+    MockNM nm4 =
+        new MockNM("127.0.0.4:2345", 8000, rm.getResourceTrackerService());
+    nm4.registerNode();
+
+    MockNM nm5 =
+        new MockNM("127.0.0.5:2345", 8000, rm.getResourceTrackerService());
+    nm5.registerNode();
+
     // Set the exist status to INVALID so that we can verify that the system
     // automatically blacklisting the node
     makeAMContainerExit(rm, amContainerId, currentNode,