AMBARI-19134 : Storm start is failing due to ClassNotFoundException org.apache.hadoop.metrics2.sink.storm.StormTimelineMetricsReporter. (avijayan)

ambari-metrics/ambari-metrics-common/src/main/java/org/apache/hadoop/metrics2/sink/timeline/AbstractTimelineMetricsSink.java

@@ -222,6 +222,11 @@ public abstract class AbstractTimelineMetricsSink {
       collectorHost = findPreferredCollectHost();
     }
 
+    if (collectorHost == null) {
+      LOG.warn("No live collector to send metrics to. Metrics to be sent will be discarded.");
+      return false;
+    }
+
     String connectUrl = getCollectorUri(collectorHost);
     String jsonData = null;
     LOG.debug("EmitMetrics connectUrl = "  + connectUrl);

ambari-metrics/ambari-metrics-common/src/test/java/org/apache/hadoop/metrics2/sink/timeline/cache/HandleConnectExceptionTest.java

@@ -130,6 +130,10 @@ public class HandleConnectExceptionTest {
       return super.emitMetrics(metrics);
     }
 
+    @Override
+    protected synchronized String findPreferredCollectHost() {
+      return "localhost";
+    }
 
   }
 }