TEZ-4561: Improve reported exception when DAGAppMaster is shutting down.

tez-dag/src/main/java/org/apache/tez/dag/app/DAGAppMaster.java

@@ -36,6 +36,7 @@
 import java.util.Arrays;
 import java.util.Calendar;
 import java.util.Collections;
+import java.util.Date;
 import java.util.EnumSet;
 import java.util.HashMap;
 import java.util.HashSet;
@@ -936,7 +937,7 @@ public void handle(DAGAppMasterEvent event) {
   protected class DAGAppMasterShutdownHandler {
     private AtomicBoolean shutdownHandled = new AtomicBoolean(false);
     private long sleepTimeBeforeExit = TezConstants.TEZ_DAG_SLEEP_TIME_BEFORE_EXIT;
-
+    Date shutdownTime;
     void setSleepTimeBeforeExit(long sleepTimeBeforeExit) {
       this.sleepTimeBeforeExit = sleepTimeBeforeExit;
     }
@@ -954,6 +955,7 @@ public void shutdown(boolean now) {
 
       synchronized (shutdownHandlerRunning) {
         shutdownHandlerRunning.set(true);
+        shutdownTime = new Date(System.currentTimeMillis());
       }
       LOG.info("Handling DAGAppMaster shutdown");
 
@@ -1680,9 +1682,11 @@ public HadoopShim getHadoopShim() {
 
     @Override
     public Map<ApplicationAccessType, String> getApplicationACLs() {
-      if (getServiceState() != STATE.STARTED) {
+      STATE serviceState = getServiceState();
+      if (serviceState != STATE.STARTED) {
         throw new TezUncheckedException(
-            "Cannot get ApplicationACLs before all services have started");
+            "Cannot get ApplicationACLs before all services have started, The current service state is " + serviceState
+                + getShutdownTimeString());
       }
       return taskSchedulerManager.getApplicationAcls();
     }
@@ -1743,6 +1747,13 @@ public void setQueueName(String queueName) {
     }
   }
 
+  private String getShutdownTimeString() {
+    if (shutdownHandler != null && shutdownHandler.shutdownTime != null) {
+      return " The shutdown hook started at " + shutdownHandler.shutdownTime;
+    }
+    return "";
+  }
+
   private static class ServiceWithDependency implements ServiceStateChangeListener {
     ServiceWithDependency(Service service) {
       this.service = service;