YARN-10459. containerLaunchedOnNode method not need to hold scheduler… (apache#3195)

Author: minni31

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

@@ -656,7 +656,7 @@ public int getNumReservedContainers(
   @SuppressWarnings("unchecked")
   public void containerLaunchedOnNode(ContainerId containerId,
       NodeId nodeId) {
-    writeLock.lock();
+    readLock.lock();
     try {
       // Inform the container
       RMContainer rmContainer = getRMContainer(containerId);
@@ -670,7 +670,7 @@ public void containerLaunchedOnNode(ContainerId containerId,
       rmContainer.handle(
           new RMContainerEvent(containerId, RMContainerEventType.LAUNCHED));
     } finally {
-      writeLock.unlock();
+      readLock.unlock();
     }
   }