diff --git a/hadoop-yarn-project/hadoop-yarn/hadoop-yarn-server/hadoop-yarn-server-resourcemanager/src/main/java/org/apache/hadoop/yarn/server/resourcemanager/webapp/RMAppAttemptBlock.java b/hadoop-yarn-project/hadoop-yarn/hadoop-yarn-server/hadoop-yarn-server-resourcemanager/src/main/java/org/apache/hadoop/yarn/server/resourcemanager/webapp/RMAppAttemptBlock.java
index 99a569af890..06763d50707 100644
--- a/hadoop-yarn-project/hadoop-yarn/hadoop-yarn-server/hadoop-yarn-server-resourcemanager/src/main/java/org/apache/hadoop/yarn/server/resourcemanager/webapp/RMAppAttemptBlock.java
+++ b/hadoop-yarn-project/hadoop-yarn/hadoop-yarn-server/hadoop-yarn-server-resourcemanager/src/main/java/org/apache/hadoop/yarn/server/resourcemanager/webapp/RMAppAttemptBlock.java
@@ -43,6 +43,7 @@ import org.apache.hadoop.yarn.server.resourcemanager.ResourceManager;
 import org.apache.hadoop.yarn.server.resourcemanager.rmapp.RMApp;
 import org.apache.hadoop.yarn.server.resourcemanager.rmapp.attempt.RMAppAttempt;
 import org.apache.hadoop.yarn.server.resourcemanager.rmapp.attempt.RMAppAttemptMetrics;
+import org.apache.hadoop.yarn.server.resourcemanager.scheduler.capacity.CapacityScheduler;
 import org.apache.hadoop.yarn.server.resourcemanager.webapp.dao.AppInfo;
 import org.apache.hadoop.yarn.server.resourcemanager.webapp.dao.ResourceRequestInfo;
 import org.apache.hadoop.yarn.server.webapp.AppAttemptBlock;
@@ -62,6 +63,228 @@ public class RMAppAttemptBlock extends AppAttemptBlock{
 
   private final ResourceManager rm;
   protected Configuration conf;
+  private final static String DIAGNOSTICS_SCRIPT_BODY = new StringBuilder()
+      .append("var refresh = false;")
+      .append("var haveGotAppDiagnostic = false;")
+      .append("function getArray(objOrArray) {")
+      .append("  if(Array.isArray(objOrArray)){")
+      .append("    return objOrArray;")
+      .append("  } else {")
+      .append("    return [objOrArray];")
+      .append("  }")
+      .append("}")
+      .append("function getTableDataFromObjectArray(objectArray, fields) {")
+      .append("  if (objectArray == undefined) {")
+      .append("    return [];")
+      .append("  }")
+      .append("  var data = [];")
+      .append("  $.each(objectArray, function(i, object) {")
+      .append("    var dataItem = [];")
+      .append("    for (var i=0; i<fields.length; i++) {")
+      .append("      dataItem.push(object[fields[i]] != undefined ? ")
+      .append("object[fields[i]] : '');")
+      .append("    }")
+      .append("    data.push(dataItem);")
+      .append("  });")
+      .append("  return data;")
+      .append("}")
+      .append("function sendRequest(requestURL, doneCallBackFunc,")
+      .append("                      failCallBackFunc) {")
+      .append(" $.ajax({")
+      .append("  type: 'GET',")
+      .append("  url: requestURL,")
+      .append("  contentType: 'text/plain'")
+      .append(" }).done(doneCallBackFunc).fail(failCallBackFunc);")
+      .append("}")
+      .append("function parseQueryAppActResponse(responseObj) {")
+      .append(" var requestDiagnostics = [], dateTime, appDiagnostic;")
+      .append(" responseObj = responseObj['appActivities'];")
+      .append(" if(responseObj.hasOwnProperty('allocations')){")
+      .append("  var allocations = getArray(responseObj['allocations']);")
+      .append("  var allocation = allocations[0];")
+      .append("  dateTime = allocation['dateTime'];")
+      .append("  if(allocation.hasOwnProperty('diagnostic')){")
+      .append("   appDiagnostic = allocation['diagnostic'];")
+      .append("  }")
+      .append("  if(allocation.hasOwnProperty('children')){")
+      .append("   var requestAllocations = ")
+      .append("     getArray(allocation['children']);")
+      .append("   $.each(requestAllocations, function (i, requestAllocation) {")
+      .append("    if(requestAllocation.hasOwnProperty('children')){")
+      .append("     var allocationAttempts = ")
+      .append("       getArray(requestAllocation['children']);")
+      .append("     var diagnosticSummary = requestAllocation.hasOwnProperty(")
+      .append("       'diagnostic')? requestAllocation['diagnostic']+'. ':'';")
+      .append("     $.each(allocationAttempts, function(i,allocationAttempt) {")
+      .append("      if (i > 0) {")
+      .append("       diagnosticSummary += ', ';")
+      .append("      }")
+      .append("      diagnosticSummary += allocationAttempt['count'] + ' ' +")
+      .append("        (allocationAttempt['count']=='1' ? 'node ' : 'nodes ')")
+      .append("        + allocationAttempt['allocationState'];")
+      .append("      if (allocationAttempt.hasOwnProperty('diagnostic')) {")
+      .append("       diagnosticSummary += ' with diagnostic:' + ")
+      .append("                   allocationAttempt['diagnostic'];")
+      .append("      }")
+      .append("     });")
+      .append("     delete requestAllocation['children'];")
+      .append("     requestAllocation['diagnostic']=diagnosticSummary;")
+      .append("    }")
+      .append("    requestDiagnostics.push(requestAllocation);")
+      .append("   });")
+      .append("  }")
+      .append(" }")
+      .append(" return [requestDiagnostics, dateTime, appDiagnostic];")
+      .append("}")
+      .append("function handleQueryAppActDone(data){")
+      .append("  console.log('App activities:', data);")
+      .append("  var results = parseQueryAppActResponse(data);")
+      .append("  console.log('parsed results:', results);")
+      .append("  var requestDiagnostics = results[0];")
+      .append("  var dateTime = results[1];")
+      .append("  var appDiagnostic = results[2];")
+      .append("  haveGotAppDiagnostic = false;")
+      .append("  if (appDiagnostic != undefined) {")
+      .append("    haveGotAppDiagnostic = true;")
+      .append("    $('#appDiagnostic').html('App diagnostic: '")
+      .append("        + appDiagnostic);")
+      .append("  }")
+      .append("  $('#diagnosticsTableDiv').empty();")
+      .append("  if (requestDiagnostics.length > 0) {")
+      .append("    haveGotAppDiagnostic = true;")
+      .append("    tableData = getTableDataFromObjectArray(requestDiagnostics,")
+      .append(" ['requestPriority', 'allocationRequestId', 'allocationState',")
+      .append(" 'diagnostic']);")
+      .append("    $('#diagnosticsTableDiv').append('<table ")
+      .append("      id=\"diagnosticsTable\"></table>');")
+      .append("    $('#diagnosticsTable').dataTable( {")
+      .append("      'aaData': tableData,")
+      .append("      'aoColumns': [")
+      .append("        { 'sTitle': 'Priority' },")
+      .append("        { 'sTitle': 'AllocationRequestId' },")
+      .append("        { 'sTitle': 'AllocationState' },")
+      .append("        { 'sTitle': 'DiagnosticSummary' }")
+      .append("      ],")
+      .append("      bJQueryUI:true, sPaginationType: 'full_numbers',")
+      .append("      iDisplayLength:20, aLengthMenu:[20, 40, 60, 80, 100]")
+      .append("    });")
+      .append("  }")
+      .append("  if (haveGotAppDiagnostic) {")
+      .append("    $('#refreshDiagnosticsBtn').attr('disabled',false);")
+      .append("    $('#diagnosticsUpdateTime').html('Updated at ' + dateTime);")
+      .append("  } else {")
+      .append("    $('#diagnosticsUpdateTime').html('');")
+      .append("    if (refresh) {")
+      .append("      refreshSchedulerDiagnostics();")
+      .append("    }")
+      .append("  }")
+      .append("}")
+      .append("function handleRequestFailure(data){")
+      .append(" alert('Request app activities REST API failed.');")
+      .append(" console.log(data);")
+      .append("}")
+      .append("function handleRefreshAppActDone(data){")
+      .append(" refresh = true;")
+      .append(" setTimeout(function(){")
+      .append("  queryAppDiagnostics();")
+      .append(" }, 2000);")
+      .append("}")
+      .append("function refreshAppDiagnostics() {")
+      .append(" $('#refreshDiagnosticsBtn').attr('disabled',true);")
+      .append(" sendRequest(refreshAppActivitiesURL,handleRefreshAppActDone,")
+      .append("             handleRequestFailure);")
+      .append("}")
+      .append("function queryAppDiagnostics() {")
+      .append(" sendRequest(getAppActivitiesURL,handleQueryAppActDone,")
+      .append("             handleRequestFailure);")
+      .append("}")
+      .append("function parseHierarchicalQueue(node, nodeInfos,")
+      .append("    parentNodePath, partition) {")
+      .append("  var nodePath = parentNodePath + '/' + node['name'];")
+      .append("  if (node.hasOwnProperty('name')){")
+      .append("    if (node['diagnostic'] == undefined || node['diagnostic']")
+      .append("      .indexOf(ignoreActivityContent) == -1){")
+      .append("     var nodeInfo = {};")
+      .append("     nodeInfo['partition'] = partition;")
+      .append("     nodeInfo['path'] = nodePath;")
+      .append("     nodeInfo['allocationState'] = node['allocationState'];")
+      .append("     nodeInfo['diagnostic'] = ")
+      .append("      node['diagnostic'] == undefined ? '':node['diagnostic'];")
+      .append("     nodeInfos.push(nodeInfo);")
+      .append("    }")
+      .append("  }")
+      .append("  if (node.hasOwnProperty('children')){")
+      .append("    var children = getArray(node['children']);")
+      .append("    $.each(children, function (i, child) {")
+      .append("      parseHierarchicalQueue(child, nodeInfos, nodePath,")
+      .append("        partition);")
+      .append("    });")
+      .append("  }")
+      .append("}")
+      .append("function parseQueueDiagnostics(data) {")
+      .append("  var nodeInfos = [], dateTime;")
+      .append("  if(data.hasOwnProperty('dateTime')){")
+      .append("      dateTime = data['dateTime'];")
+      .append("  }")
+      .append("  if(data.hasOwnProperty('allocations')){")
+      .append("    var allocations = getArray(data['allocations']);")
+      .append("    $.each(allocations, function (i, allocation) {")
+      .append("      if (allocation.hasOwnProperty('root')) {")
+      .append("        var root = allocation['root'];")
+      .append("        var partition = allocation['partition'];")
+      .append("        parseHierarchicalQueue(root, nodeInfos, '', partition);")
+      .append("      }")
+      .append("    });")
+      .append("  }")
+      .append("  return [nodeInfos, dateTime];")
+      .append("}")
+      .append("function handleRefreshSchedulerActDone(data){")
+      .append(" console.log('handleRefreshSchedulerActDone', data);")
+      .append(" setTimeout(function(){")
+      .append("  querySchedulerDiagnostics();")
+      .append("  $('#refreshDiagnosticsBtn').attr('disabled',false);")
+      .append(" }, 100);")
+      .append("}")
+      .append("function handleQuerySchedulerActDone(data){")
+      .append("  console.log('Scheduler activities:', data);")
+      .append("  data = data['activities'];")
+      .append("  var results = parseQueueDiagnostics(data);")
+      .append("  var nodeInfos = results[0];")
+      .append("  var dateTime = results[1];")
+      .append("  $('#diagnosticsTableDiv').empty();")
+      .append("  if(dateTime != undefined){")
+      .append("   $('#diagnosticsUpdateTime').html('App diagnostics not found!")
+      .append(" Got useful scheduler activities updated at '+dateTime);")
+      .append("    tableData = getTableDataFromObjectArray(nodeInfos, ")
+      .append(" ['partition', 'path', 'allocationState', 'diagnostic']);")
+      .append("    $('#diagnosticsTableDiv').append('<table ")
+      .append("      id=\"diagnosticsTable\"></table>');")
+      .append("    $('#diagnosticsTable').dataTable({")
+      .append("      'aaData': tableData,")
+      .append("      'aoColumns': [")
+      .append("        { 'sTitle': 'Partition' },")
+      .append("        { 'sTitle': 'SchedulingNode' },")
+      .append("        { 'sTitle': 'AllocationState' },")
+      .append("        { 'sTitle': 'Diagnostic' }")
+      .append("      ],")
+      .append("      bJQueryUI:true, sPaginationType: 'full_numbers',")
+      .append("      iDisplayLength:20, aLengthMenu:[20, 40, 60, 80, 100]")
+      .append("    });")
+      .append("  } else if(data.hasOwnProperty('diagnostic')){")
+      .append("    $('#diagnosticsUpdateTime').html(data['diagnostic']);")
+      .append("  }")
+      .append("  $('#refreshDiagnosticsBtn').attr('disabled',false);")
+      .append("}")
+      .append("function refreshSchedulerDiagnostics() {")
+      .append(" $('#refreshDiagnosticsBtn').attr('disabled',true);")
+      .append(" sendRequest(schedulerActivitiesURL,")
+      .append("   handleRefreshSchedulerActDone,handleRequestFailure);")
+      .append("}")
+      .append("function querySchedulerDiagnostics() {")
+      .append(" sendRequest(schedulerActivitiesURL,")
+      .append("   handleQuerySchedulerActDone,handleRequestFailure);")
+      .append("}")
+      .append("queryAppDiagnostics();").toString();
 
   @Inject
   RMAppAttemptBlock(ViewContext ctx, ResourceManager rm, Configuration conf) {
@@ -137,6 +360,10 @@ public class RMAppAttemptBlock extends AppAttemptBlock{
     html.script().$type("text/javascript")
         .__("var resourceRequestsTableData=" + resourceRequestTableData).__();
     tbody.__().__();
+
+    // create diagnostics table when CS is enabled
+    createDiagnosticsTable(html, div);
+
     div.__();
   }
 
@@ -311,4 +538,52 @@ public class RMAppAttemptBlock extends AppAttemptBlock{
     return rm.getClientRMService().getApplicationAttemptReport(request)
         .getApplicationAttemptReport();
   }
+
+  private void createDiagnosticsTable(Block html, DIV<Hamlet> parentDiv) {
+    if (!(rm.getResourceScheduler() instanceof CapacityScheduler)) {
+      return;
+    }
+    String appActivitiesURL =
+        new StringBuilder().append(RMWSConsts.RM_WEB_SERVICE_PATH).append(
+            RMWSConsts.SCHEDULER_APP_ACTIVITIES.replace("{appid}",
+                this.appAttemptId.getApplicationId().toString())).append("?")
+            .toString();
+    String refreshAppActivitiesURL = appActivitiesURL + "actions=refresh";
+    String getAppActivitiesURL = appActivitiesURL
+        + "actions=get&groupBy=diagnostic&summarize=true";
+    String refreshAndGetAppActivitiesURL = appActivitiesURL
+        + "actions=refresh&actions=get&groupBy=diagnostic&summarize=true";
+    String schedulerActivitiesURL =
+        new StringBuilder().append(RMWSConsts.RM_WEB_SERVICE_PATH)
+            .append(RMWSConsts.SCHEDULER_ACTIVITIES).append("?")
+            .append(RMWSConsts.GROUP_BY).append("=diagnostic").toString();
+
+    DIV<DIV<Hamlet>> div = parentDiv.div();
+    div.p().__("Diagnostics in cache ").__("(For more details refer to ")
+        .a(refreshAndGetAppActivitiesURL, "App Activities").__(" or ")
+        .a(schedulerActivitiesURL, "Scheduler Activities").__(")").__();
+    div.button().$id("refreshDiagnosticsBtn")
+        .$style("border-style: solid; border-color: #000000; border-width: 1px;"
+                + " cursor: hand; cursor: pointer; border-radius: 4px")
+        .$onclick("refreshAppDiagnostics()").b("Refresh").__();
+    div.p().$id("diagnosticsUpdateTime").__();
+    div.p().$id("appDiagnostic").__();
+    div.div("#diagnosticsTableDiv").__();
+
+    div.__();
+
+    StringBuilder script = new StringBuilder();
+    script
+        .append("var refreshAppActivitiesURL = '")
+        .append(refreshAppActivitiesURL).append("';")
+        .append("var getAppActivitiesURL = '")
+        .append(getAppActivitiesURL).append("';")
+        .append("var schedulerActivitiesURL = '")
+        .append(schedulerActivitiesURL).append("';")
+        .append("var ignoreActivityContent = '")
+        .append("does not need more resource';")
+        .append(DIAGNOSTICS_SCRIPT_BODY);
+
+    html.script().$type("text/javascript").__(script.toString()).__();
+  }
 }