Fixed potentially thread unsafe initialization.

Change-Id: I047bcd9358a544723603a069faa234c00ba6b757

@@ -8,7 +8,7 @@ import java.util.concurrent.atomic.AtomicInteger;
  */
 public final class ApplicationId {
 
-    private static AtomicInteger idDispenser;
+    private static final AtomicInteger ID_DISPENCER = new AtomicInteger(1);
     private final Integer id;
 
     // Ban public construction
@@ -50,10 +50,7 @@ public final class ApplicationId {
      * @return app id
      */
     public static ApplicationId getAppId() {
-        if (ApplicationId.idDispenser == null) {
-            ApplicationId.idDispenser = new AtomicInteger(1);
-        }
-        return new ApplicationId(ApplicationId.idDispenser.getAndIncrement());
+        return new ApplicationId(ApplicationId.ID_DISPENCER.getAndIncrement());
     }
 
 }

@@ -8,7 +8,7 @@ import org.jboss.netty.util.HashedWheelTimer;
  */
 public final class Timer {
 
-    private static HashedWheelTimer timer;
+    private static volatile HashedWheelTimer timer;
 
     // Ban public construction
     private Timer() {
@@ -21,10 +21,16 @@ public final class Timer {
      */
     public static HashedWheelTimer getTimer() {
         if (Timer.timer == null) {
+            initTimer();
+        }
+        return Timer.timer;
+    }
+
+    private static synchronized  void initTimer() {
+        if (Timer.timer == null) {
             Timer.timer = new HashedWheelTimer();
             Timer.timer.start();
         }
-        return Timer.timer;
     }
 
 }