YARN-2608. FairScheduler: Potential deadlocks in loading alloc files and clock access. (Wei Yan via kasha)

(cherry picked from commit c9811af09a3d3f9f2f1b86fc9d6f2763d3225e44)

hadoop-yarn-project/CHANGES.txt

@@ -420,6 +420,9 @@ Release 2.6.0 - UNRELEASED
     YARN-2523. ResourceManager UI showing negative value for "Decommissioned
     Nodes" field (Rohith via jlowe)
 
+    YARN-2608. FairScheduler: Potential deadlocks in loading alloc files and 
+    clock access. (Wei Yan via kasha)
+
 Release 2.5.1 - 2014-09-05
 
   INCOMPATIBLE CHANGES

hadoop-yarn-project/hadoop-yarn/hadoop-yarn-server/hadoop-yarn-server-resourcemanager/src/main/java/org/apache/hadoop/yarn/server/resourcemanager/scheduler/fair/FairScheduler.java

@@ -117,7 +117,7 @@ public class FairScheduler extends
 
   private Resource incrAllocation;
   private QueueManager queueMgr;
-  private Clock clock;
+  private volatile Clock clock;
   private boolean usePortForNodeName;
 
   private static final Log LOG = LogFactory.getLog(FairScheduler.class);
@@ -555,11 +555,12 @@ public class FairScheduler extends
     return continuousSchedulingSleepMs;
   }
 
-  public synchronized Clock getClock() {
+  public Clock getClock() {
     return clock;
   }
 
-  protected synchronized void setClock(Clock clock) {
+  @VisibleForTesting
+  void setClock(Clock clock) {
     this.clock = clock;
   }
 
@@ -1204,8 +1205,8 @@ public class FairScheduler extends
     this.rmContext = rmContext;
   }
 
-  private synchronized void initScheduler(Configuration conf)
+  private void initScheduler(Configuration conf) throws IOException {
-      throws IOException {
+    synchronized (this) {
       this.conf = new FairSchedulerConfiguration(conf);
       validateConf(this.conf);
       minimumAllocation = this.conf.getMinimumAllocation();
@@ -1263,6 +1264,7 @@ public class FairScheduler extends
         schedulingThread.setName("FairSchedulerContinuousScheduling");
         schedulingThread.setDaemon(true);
       }
+    }
 
     allocsLoader.init(conf);
     allocsLoader.setReloadListener(new AllocationReloadListener());
@@ -1321,7 +1323,7 @@ public class FairScheduler extends
   }
 
   @Override
-  public synchronized void reinitialize(Configuration conf, RMContext rmContext)
+  public void reinitialize(Configuration conf, RMContext rmContext)
       throws IOException {
     try {
       allocsLoader.reloadAllocations();