[SPARK-5771] Master UI inconsistently displays application cores

core/src/main/scala/org/apache/spark/deploy/DeployMessage.scala

@@ -101,6 +101,8 @@ private[deploy] object DeployMessages {
   case class RegisterApplication(appDescription: ApplicationDescription)
     extends DeployMessage
 
+  case class UnregisterApplication(appId: String)
+
   case class MasterChangeAcknowledged(appId: String)
 
   // Master to AppClient

core/src/main/scala/org/apache/spark/deploy/client/AppClient.scala

@@ -157,6 +157,7 @@ private[spark] class AppClient(
 
       case StopAppClient =>
         markDead("Application has been stopped.")
+        master ! UnregisterApplication(appId)
         sender ! true
         context.stop(self)
     }

core/src/main/scala/org/apache/spark/deploy/master/ApplicationInfo.scala

@@ -111,6 +111,10 @@ private[deploy] class ApplicationInfo(
     endTime = System.currentTimeMillis()
   }
 
+  private[master] def isFinished: Boolean = {
+    state != ApplicationState.WAITING && state != ApplicationState.RUNNING
+  }
+
   def duration: Long = {
     if (endTime != -1) {
       endTime - startTime

core/src/main/scala/org/apache/spark/deploy/master/Master.scala

@@ -339,7 +339,11 @@ private[master] class Master(
           if (ExecutorState.isFinished(state)) {
             // Remove this executor from the worker and app
             logInfo(s"Removing executor ${exec.fullId} because it is $state")
-            appInfo.removeExecutor(exec)
+            // If an application has already finished, preserve its
+            // state to display its information properly on the UI
+            if (!appInfo.isFinished) {
+              appInfo.removeExecutor(exec)
+            }
             exec.worker.removeExecutor(exec)
 
             val normalExit = exitStatus == Some(0)
@@ -428,6 +432,10 @@ private[master] class Master(
       if (canCompleteRecovery) { completeRecovery() }
     }
 
+    case UnregisterApplication(applicationId) =>
+      logInfo(s"Received unregister request from application $applicationId")
+      idToApp.get(applicationId).foreach(finishApplication)
+
     case DisassociatedEvent(_, address, _) => {
       // The disconnected client could've been either a worker or an app; remove whichever it was
       logInfo(s"$address got disassociated, removing it.")