--- a/src/main/java/jp/ac/u_ryukyu/treevnc/MulticastQueue.java	Fri Apr 18 11:17:34 2014 +0900
+++ b/src/main/java/jp/ac/u_ryukyu/treevnc/MulticastQueue.java	Mon Apr 28 18:25:23 2014 +0900
@@ -1,5 +1,6 @@
 package jp.ac.u_ryukyu.treevnc;
 
+import java.nio.ByteBuffer;
 import java.util.concurrent.CountDownLatch;
 
 public class MulticastQueue<T>
@@ -11,7 +12,40 @@
 	{
 		tail = new Node<T>(null);
 	}
+	
+	/**
+	 * @param size
+	 * @return
+	 * 
+	 * try to allocate byteBuffer.
+	 * wait until heap is available.
+	 * 
+	 * 
+	 */
+	public ByteBuffer allocate(int size)
+	{
+		ByteBuffer b=null;
+		while(true){
+			try{
+				b = ByteBuffer.allocate(size);
+			}catch(OutOfMemoryError e){
+				System.err.println("multicastqueue : wait for heap : " + e);
+			}
+			if(b!=null){
+				break;
+			}
+			try {
+				wait();
+			} catch (InterruptedException e) {
+			}
+		}		
+		return b;
+	}
 
+	public synchronized void heapAvailable() {
+		notifyAll();
+	}
+	
 	public synchronized void put(T item)
 	{
 		Node<T> next = new Node<T>(item);
@@ -43,7 +77,6 @@
 				}catch(InterruptedException _e){
 					continue;
 				}
-//				item = node.getItem();
 				item = next.getItem();				
 				node = next;
 			} while ( item == null);