YARN-8022. ResourceManager UI cluster/app/<app-id> page fails to render. Contributed by Tarun Parimi.

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

@@ -109,8 +109,7 @@ public class AppBlock extends HtmlBlock {
       final GetApplicationReportRequest request =
           GetApplicationReportRequest.newInstance(appID);
       if (callerUGI == null) {
-        appReport =
-            appBaseProt.getApplicationReport(request).getApplicationReport();
+        appReport = getApplicationReport(request);
       } else {
         appReport = callerUGI.doAs(
             new PrivilegedExceptionAction<ApplicationReport> () {
@@ -143,14 +142,19 @@ public class AppBlock extends HtmlBlock {
     try {
       final GetApplicationAttemptsRequest request =
           GetApplicationAttemptsRequest.newInstance(appID);
-      attempts = callerUGI.doAs(
+      if (callerUGI == null) {
+        attempts = getApplicationAttemptsReport(request);
+      } else {
+        attempts = callerUGI.doAs(
           new PrivilegedExceptionAction<Collection<
               ApplicationAttemptReport>>() {
             @Override
-            public Collection<ApplicationAttemptReport> run() throws Exception {
+            public Collection<ApplicationAttemptReport> run()
+                throws Exception {
               return getApplicationAttemptsReport(request);
             }
           });
+      }
     } catch (Exception e) {
       String message =
           "Failed to read the attempts of the application " + appID + ".";
@@ -204,36 +208,55 @@ public class AppBlock extends HtmlBlock {
     String schedulerPath = WebAppUtils.getResolvedRMWebAppURLWithScheme(conf) +
         "/cluster/scheduler?openQueues=" + app.getQueue();
 
+    generateOverviewTable(app, schedulerPath, webUiType, appReport);
+
+    createApplicationMetricsTable(html);
+
+    html.__(InfoBlock.class);
+
+    generateApplicationTable(html, callerUGI, attempts);
+
+  }
+
+  /**
+   * Generate overview table for app web page.
+   * @param app app info.
+   * @param schedulerPath schedule path.
+   * @param webUiType web ui type.
+   * @param appReport app report.
+   */
+  private void generateOverviewTable(AppInfo app, String schedulerPath,
+      String webUiType, ApplicationReport appReport) {
     ResponseInfo overviewTable = info("Application Overview")
-      .__("User:", schedulerPath, app.getUser())
-      .__("Name:", app.getName())
-      .__("Application Type:", app.getType())
-      .__("Application Tags:",
-        app.getApplicationTags() == null ? "" : app.getApplicationTags())
-      .__("Application Priority:", clarifyAppPriority(app.getPriority()))
-      .__(
-        "YarnApplicationState:",
-        app.getAppState() == null ? UNAVAILABLE : clarifyAppState(app
-          .getAppState()))
-      .__("Queue:", schedulerPath, app.getQueue())
-      .__("FinalStatus Reported by AM:",
-        clairfyAppFinalStatus(app.getFinalAppStatus()))
-      .__("Started:", Times.format(app.getStartedTime()))
-      .__(
-        "Elapsed:",
-        StringUtils.formatTime(Times.elapsed(app.getStartedTime(),
-          app.getFinishedTime())))
-      .__(
-        "Tracking URL:",
-        app.getTrackingUrl() == null
-            || app.getTrackingUrl().equals(UNAVAILABLE) ? null : root_url(app
-          .getTrackingUrl()),
-        app.getTrackingUrl() == null
-            || app.getTrackingUrl().equals(UNAVAILABLE) ? "Unassigned" : app
-          .getAppState() == YarnApplicationState.FINISHED
-            || app.getAppState() == YarnApplicationState.FAILED
-            || app.getAppState() == YarnApplicationState.KILLED ? "History"
-            : "ApplicationMaster");
+        .__("User:", schedulerPath, app.getUser())
+        .__("Name:", app.getName())
+        .__("Application Type:", app.getType())
+        .__("Application Tags:",
+            app.getApplicationTags() == null ? "" : app.getApplicationTags())
+        .__("Application Priority:", clarifyAppPriority(app.getPriority()))
+        .__(
+            "YarnApplicationState:",
+            app.getAppState() == null ? UNAVAILABLE : clarifyAppState(app
+                .getAppState()))
+        .__("Queue:", schedulerPath, app.getQueue())
+        .__("FinalStatus Reported by AM:",
+            clairfyAppFinalStatus(app.getFinalAppStatus()))
+        .__("Started:", Times.format(app.getStartedTime()))
+        .__(
+            "Elapsed:",
+            StringUtils.formatTime(Times.elapsed(app.getStartedTime(),
+                app.getFinishedTime())))
+        .__(
+            "Tracking URL:",
+            app.getTrackingUrl() == null
+                || app.getTrackingUrl().equals(UNAVAILABLE) ? null : root_url(app
+                .getTrackingUrl()),
+            app.getTrackingUrl() == null
+                || app.getTrackingUrl().equals(UNAVAILABLE) ? "Unassigned" : app
+                .getAppState() == YarnApplicationState.FINISHED
+                || app.getAppState() == YarnApplicationState.FAILED
+                || app.getAppState() == YarnApplicationState.KILLED ? "History"
+                : "ApplicationMaster");
     if (webUiType != null
         && webUiType.equals(YarnWebParams.RM_WEB_UI)) {
       LogAggregationStatus status = getLogAggregationStatus();
@@ -265,37 +288,6 @@ public class AppBlock extends HtmlBlock {
     overviewTable.__("AM container Node Label expression:",
         app.getAmNodeLabelExpression() == null ? "<Not set>"
             : app.getAmNodeLabelExpression());
-
-    try {
-      final GetApplicationAttemptsRequest request =
-          GetApplicationAttemptsRequest.newInstance(appID);
-      if (callerUGI == null) {
-        attempts = appBaseProt.getApplicationAttempts(request)
-            .getApplicationAttemptList();
-      } else {
-        attempts = callerUGI.doAs(
-            new PrivilegedExceptionAction<Collection<ApplicationAttemptReport>> () {
-          @Override
-          public Collection<ApplicationAttemptReport> run() throws Exception {
-            return appBaseProt.getApplicationAttempts(request)
-                .getApplicationAttemptList();
-          }
-        });
-      }
-    } catch (Exception e) {
-      String message =
-          "Failed to read the attempts of the application " + appID + ".";
-      LOG.error(message, e);
-      html.p().__(message).__();
-      return;
-    }
-
-    createApplicationMetricsTable(html);
-
-    html.__(InfoBlock.class);
-
-    generateApplicationTable(html, callerUGI, attempts);
-
   }
 
   protected void generateApplicationTable(Block html,