YARN-3973. Recent changes to application priority management break reservation system from YARN-1051 (Carlo Curino via wangda)

hadoop-yarn-project/CHANGES.txt

@@ -667,7 +667,8 @@ Release 2.8.0 - UNRELEASED
 
     YARN-3956. Fix TestNodeManagerHardwareUtils fails on Mac (Varun Vasudev via wangda)
 
-    YARN-3941. Proportional Preemption policy should try to avoid sending duplicate PREEMPT_CONTAINER event to scheduler. (Sunil G via wangda)
+    YARN-3941. Proportional Preemption policy should try to avoid sending duplicate 
+    PREEMPT_CONTAINER event to scheduler. (Sunil G via wangda)
 
     YARN-3900. Protobuf layout of yarn_security_token causes errors in other protos
     that include it (adhoot via rkanter)
@@ -678,6 +679,9 @@ Release 2.8.0 - UNRELEASED
     YARN-3957. FairScheduler NPE In FairSchedulerQueueInfo causing scheduler page to 
     return 500. (Anubhav Dhoot via kasha)
 
+    YARN-3973. Recent changes to application priority management break 
+    reservation system from YARN-1051. (Carlo Curino via wangda)
+
 Release 2.7.2 - UNRELEASED
 
   INCOMPATIBLE CHANGES

hadoop-yarn-project/hadoop-yarn/hadoop-yarn-server/hadoop-yarn-server-resourcemanager/src/main/java/org/apache/hadoop/yarn/server/resourcemanager/scheduler/capacity/CapacityScheduler.java

@@ -1867,7 +1867,7 @@ public class CapacityScheduler extends
 
   private Priority getDefaultPriorityForQueue(String queueName) {
     Queue queue = getQueue(queueName);
-    if (null == queue) {
+    if (null == queue || null == queue.getDefaultApplicationPriority()) {
       // Return with default application priority
       return Priority.newInstance(CapacitySchedulerConfiguration
           .DEFAULT_CONFIGURATION_APPLICATION_PRIORITY);