YARN-3751. Fixed AppInfo to check if used resources are null. Contributed by Sunil G.

(cherry picked from commit dbc4f64937ea2b4c941a3ac49afc4eeba3f5b763)

hadoop-yarn-project/CHANGES.txt

@@ -431,6 +431,9 @@ Release 2.8.0 - UNRELEASED
     YARN-3740. Fixed the typo in the configuration name:
     APPLICATION_HISTORY_PREFIX_MAX_APPS. (Xuan Gong via zjshen)
 
+    YARN-3751. Fixed AppInfo to check if used resources are null. (Sunil G via
+    zjshen)
+
 Release 2.7.1 - UNRELEASED
 
   INCOMPATIBLE CHANGES

hadoop-yarn-project/hadoop-yarn/hadoop-yarn-server/hadoop-yarn-server-common/src/main/java/org/apache/hadoop/yarn/server/webapp/dao/AppInfo.java

@@ -86,12 +86,14 @@ public class AppInfo {
     elapsedTime = Times.elapsed(startedTime, finishedTime);
     finalAppStatus = app.getFinalApplicationStatus();
     if (app.getApplicationResourceUsageReport() != null) {
-      runningContainers =
-          app.getApplicationResourceUsageReport().getNumUsedContainers();
-      allocatedCpuVcores = app.getApplicationResourceUsageReport()
-          .getUsedResources().getVirtualCores();
-      allocatedMemoryMB = app.getApplicationResourceUsageReport()
-          .getUsedResources().getMemory();
+      runningContainers = app.getApplicationResourceUsageReport()
+          .getNumUsedContainers();
+      if (app.getApplicationResourceUsageReport().getUsedResources() != null) {
+        allocatedCpuVcores = app.getApplicationResourceUsageReport()
+            .getUsedResources().getVirtualCores();
+        allocatedMemoryMB = app.getApplicationResourceUsageReport()
+            .getUsedResources().getMemory();
+      }
     }
     progress = app.getProgress() * 100; // in percent
     if (app.getApplicationTags() != null && !app.getApplicationTags().isEmpty()) {