YARN-3487. CapacityScheduler scheduler lock obtained unnecessarily when calling getQueue (Jason Lowe via wangda)

(cherry picked from commit f47a5763acd55cb0b3f16152c7f8df06ec0e09a9)
(cherry picked from commit 3316cd4357ff6ccc4c76584813092adb1c2b4d43)
(cherry picked from commit 24d45ee9544abcfcf9e611ab835ec2f824333670)

hadoop-yarn-project/CHANGES.txt

@@ -126,6 +126,9 @@ Release 2.6.1 - UNRELEASED
     YARN-3493. RM fails to come up with error "Failed to load/recover state" 
     when mem settings are changed. (Jian He via wangda)
 
+    YARN-3487. CapacityScheduler scheduler lock obtained unnecessarily when 
+    calling getQueue (Jason Lowe via wangda)
+
 Release 2.6.0 - 2014-11-18
 
   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

@@ -604,7 +604,7 @@ public class CapacityScheduler extends
     return queue;
   }
 
-  public synchronized CSQueue getQueue(String queueName) {
+  public CSQueue getQueue(String queueName) {
     if (queueName == null) {
       return null;
     }
@@ -902,11 +902,7 @@ public class CapacityScheduler extends
       boolean includeChildQueues, boolean recursive) 
   throws IOException {
     CSQueue queue = null;
-
-    synchronized (this) {
-      queue = this.queues.get(queueName); 
-    }
-
+    queue = this.queues.get(queueName);
     if (queue == null) {
       throw new IOException("Unknown queue: " + queueName);
     }