diff --git a/hadoop-yarn-project/CHANGES.txt b/hadoop-yarn-project/CHANGES.txt
index e9a7c588d5..e00e447844 100644
--- a/hadoop-yarn-project/CHANGES.txt
+++ b/hadoop-yarn-project/CHANGES.txt
@@ -599,6 +599,9 @@ Release 2.7.0 - UNRELEASED
     YARN-2899. Run TestDockerContainerExecutorWithMocks on Linux only.
     (Ming Ma via cnauroth)
 
+    YARN-2749. Fix some testcases from TestLogAggregationService fails in trunk. 
+    (Xuan Gong via junping_du)
+
 Release 2.6.0 - 2014-11-18
 
   INCOMPATIBLE CHANGES
diff --git a/hadoop-yarn-project/hadoop-yarn/hadoop-yarn-server/hadoop-yarn-server-nodemanager/src/main/java/org/apache/hadoop/yarn/server/nodemanager/containermanager/logaggregation/AppLogAggregatorImpl.java b/hadoop-yarn-project/hadoop-yarn/hadoop-yarn-server/hadoop-yarn-server-nodemanager/src/main/java/org/apache/hadoop/yarn/server/nodemanager/containermanager/logaggregation/AppLogAggregatorImpl.java
index 20887b6648..8eb00f4f65 100644
--- a/hadoop-yarn-project/hadoop-yarn/hadoop-yarn-server/hadoop-yarn-server-nodemanager/src/main/java/org/apache/hadoop/yarn/server/nodemanager/containermanager/logaggregation/AppLogAggregatorImpl.java
+++ b/hadoop-yarn-project/hadoop-yarn/hadoop-yarn-server/hadoop-yarn-server-nodemanager/src/main/java/org/apache/hadoop/yarn/server/nodemanager/containermanager/logaggregation/AppLogAggregatorImpl.java
@@ -117,6 +117,8 @@ public class AppLogAggregatorImpl implements AppLogAggregator {
   private final int retentionSize;
   private final long rollingMonitorInterval;
   private final NodeId nodeId;
+  // This variable is only for testing
+  private final AtomicBoolean waiting = new AtomicBoolean(false);
 
   private final Map<ContainerId, ContainerLogAggregator> containerLogAggregators =
       new HashMap<ContainerId, ContainerLogAggregator>();
@@ -391,6 +393,7 @@ private void doAppLogAggregation() {
     while (!this.appFinishing.get() && !this.aborted.get()) {
       synchronized(this) {
         try {
+          waiting.set(true);
           if (this.rollingMonitorInterval > 0) {
             wait(this.rollingMonitorInterval * 1000);
             if (this.appFinishing.get() || this.aborted.get()) {
@@ -507,7 +510,19 @@ public synchronized void abortLogAggregation() {
 
   @Private
   @VisibleForTesting
+  // This is only used for testing.
+  // This will wake the log aggregation thread that is waiting for
+  // rollingMonitorInterval.
+  // To use this method, make sure the log aggregation thread is running
+  // and waiting for rollingMonitorInterval.
   public synchronized void doLogAggregationOutOfBand() {
+    while(!waiting.get()) {
+      try {
+        wait(200);
+      } catch (InterruptedException e) {
+        // Do Nothing
+      }
+    }
     LOG.info("Do OutOfBand log aggregation");
     this.notifyAll();
   }