diff --git a/genomix/genomix-pregelix/src/main/java/edu/uci/ics/genomix/pregelix/io/LogAlgorithmMessageWritable.java b/genomix/genomix-pregelix/src/main/java/edu/uci/ics/genomix/pregelix/io/LogAlgorithmMessageWritable.java
index 2e793da..c2d3f1c 100644
--- a/genomix/genomix-pregelix/src/main/java/edu/uci/ics/genomix/pregelix/io/LogAlgorithmMessageWritable.java
+++ b/genomix/genomix-pregelix/src/main/java/edu/uci/ics/genomix/pregelix/io/LogAlgorithmMessageWritable.java
@@ -7,6 +7,7 @@
 import org.apache.hadoop.io.WritableComparable;
 
 import edu.uci.ics.genomix.pregelix.operator.ThreeStepLogAlgorithmForPathMergeVertex;
+import edu.uci.ics.genomix.pregelix.type.CheckMessage;
 import edu.uci.ics.genomix.type.KmerBytesWritable;
 import edu.uci.ics.genomix.type.VKmerBytesWritable;
 
@@ -20,28 +21,39 @@
 	private KmerBytesWritable sourceVertexId;
 	private VKmerBytesWritable chainVertexId;
 	private byte adjMap;
-	private int message;
-	private int sourceVertexState;
+	private byte message;
+	
+	private byte checkMessage;
 	
 	public LogAlgorithmMessageWritable(){
 		sourceVertexId = new VKmerBytesWritable(ThreeStepLogAlgorithmForPathMergeVertex.kmerSize);
 		chainVertexId = new VKmerBytesWritable(ThreeStepLogAlgorithmForPathMergeVertex.kmerSize);
+		checkMessage = 0;
 	}
 	
-	public void set(KmerBytesWritable sourceVertexId, VKmerBytesWritable chainVertexId, byte adjMap, int message, int sourceVertexState){
-		this.sourceVertexId.set(sourceVertexId);
-		this.chainVertexId.set(chainVertexId);
-		this.adjMap = adjMap;
+	public void set(KmerBytesWritable sourceVertexId, VKmerBytesWritable chainVertexId, byte adjMap, byte message){
+		checkMessage = 0;
+		if(sourceVertexId != null){
+			checkMessage |= CheckMessage.SOURCE;
+			this.sourceVertexId.set(sourceVertexId);
+		}
+		if(chainVertexId != null){
+			checkMessage |= CheckMessage.CHAIN;
+			this.chainVertexId.set(chainVertexId);
+		}
+		if(adjMap != 0){
+			checkMessage |= CheckMessage.ADJMAP;
+			this.adjMap = adjMap;
+		}
 		this.message = message;
-		this.sourceVertexState = sourceVertexState;
 	}
 	
 	public void reset(){
-		//sourceVertexId.reset(ThreeStepLogAlgorithmForPathMergeVertex.kmerSize);
+		checkMessage = 0;
 		chainVertexId.reset(ThreeStepLogAlgorithmForPathMergeVertex.kmerSize);
 		adjMap = (byte)0;
 		message = 0;
-		sourceVertexState = 0;
+		//sourceVertexState = 0;
 	}
 
 	public KmerBytesWritable getSourceVertexId() {
@@ -49,7 +61,10 @@
 	}
 
 	public void setSourceVertexId(KmerBytesWritable sourceVertexId) {
-		this.sourceVertexId.set(sourceVertexId);
+		if(sourceVertexId != null){
+			checkMessage |= CheckMessage.SOURCE;
+			this.sourceVertexId.set(sourceVertexId);
+		}
 	}
 
 	public byte getAdjMap() {
@@ -68,42 +83,40 @@
 		this.chainVertexId.set(chainVertexId);
 	}
 
-	public int getMessage() {
+	public byte getMessage() {
 		return message;
 	}
 
-	public void setMessage(int message) {
+	public void setMessage(byte message) {
 		this.message = message;
 	}
 
-	public int getSourceVertexState() {
-		return sourceVertexState;
-	}
-
-	public void setSourceVertexState(int sourceVertexState) {
-		this.sourceVertexState = sourceVertexState;
-	}
-
 	public int getLengthOfChain() {
 		return chainVertexId.getKmerLength();
 	}
 	
 	@Override
 	public void write(DataOutput out) throws IOException {
-		sourceVertexId.write(out);
-		chainVertexId.write(out);
-		out.write(adjMap);
-		out.writeInt(message);
-		out.writeInt(sourceVertexState);
+		out.writeByte(checkMessage);
+		if((checkMessage & CheckMessage.SOURCE) != 0)
+			sourceVertexId.write(out);
+		if((checkMessage & CheckMessage.CHAIN) != 0)
+			chainVertexId.write(out);
+		if((checkMessage & CheckMessage.ADJMAP) != 0)
+			out.write(adjMap);
+		out.writeByte(message);
 	}
 
 	@Override
 	public void readFields(DataInput in) throws IOException {
-		sourceVertexId.readFields(in);
-		chainVertexId.readFields(in);
-		adjMap = in.readByte();
-		message = in.readInt();
-		sourceVertexState = in.readInt();
+		checkMessage = in.readByte();
+		if((checkMessage & CheckMessage.SOURCE) != 0)
+			sourceVertexId.readFields(in);
+		if((checkMessage & CheckMessage.CHAIN) != 0)
+			chainVertexId.readFields(in);
+		if((checkMessage & CheckMessage.ADJMAP) != 0)
+			adjMap = in.readByte();
+		message = in.readByte();
 	}
 
 	 @Override
diff --git a/genomix/genomix-pregelix/src/main/java/edu/uci/ics/genomix/pregelix/io/ValueStateWritable.java b/genomix/genomix-pregelix/src/main/java/edu/uci/ics/genomix/pregelix/io/ValueStateWritable.java
index 392acab..8931dcc 100644
--- a/genomix/genomix-pregelix/src/main/java/edu/uci/ics/genomix/pregelix/io/ValueStateWritable.java
+++ b/genomix/genomix-pregelix/src/main/java/edu/uci/ics/genomix/pregelix/io/ValueStateWritable.java
@@ -14,7 +14,7 @@
 public class ValueStateWritable implements WritableComparable<ValueStateWritable> {
 
 	private byte adjMap;
-	private int state;
+	private byte state;
 	private VKmerBytesWritable mergeChain;
 
 	public ValueStateWritable() {
@@ -22,13 +22,13 @@
 		mergeChain = new VKmerBytesWritable(NaiveAlgorithmForPathMergeVertex.kmerSize);
 	}
 
-	public ValueStateWritable(byte adjMap, int state, VKmerBytesWritable mergeChain) {
+	public ValueStateWritable(byte adjMap, byte state, VKmerBytesWritable mergeChain) {
 		this.adjMap = adjMap;
 		this.state = state;
 		this.mergeChain.set(mergeChain);
 	}
 	
-	public void set(byte adjMap, int state, VKmerBytesWritable mergeChain){
+	public void set(byte adjMap, byte state, VKmerBytesWritable mergeChain){
 		this.adjMap = adjMap;
 		this.state = state;
 		this.mergeChain.set(mergeChain);
@@ -42,11 +42,11 @@
 		this.adjMap = adjMap;
 	}
 
-	public int getState() {
+	public byte getState() {
 		return state;
 	}
 
-	public void setState(int state) {
+	public void setState(byte state) {
 		this.state = state;
 	}
 
@@ -69,14 +69,14 @@
 	@Override
 	public void readFields(DataInput in) throws IOException {
 		adjMap = in.readByte();
-		state = in.readInt();
+		state = in.readByte();
 		mergeChain.readFields(in);
 	}
 
 	@Override
 	public void write(DataOutput out) throws IOException {
 		out.writeByte(adjMap);
-		out.writeInt(state);
+		out.writeByte(state);
 		mergeChain.write(out);
 	}
 
diff --git a/genomix/genomix-pregelix/src/main/java/edu/uci/ics/genomix/pregelix/log/LogAlgorithmLogFormatter.java b/genomix/genomix-pregelix/src/main/java/edu/uci/ics/genomix/pregelix/log/LogAlgorithmLogFormatter.java
index d4f03ee..a615334 100644
--- a/genomix/genomix-pregelix/src/main/java/edu/uci/ics/genomix/pregelix/log/LogAlgorithmLogFormatter.java
+++ b/genomix/genomix-pregelix/src/main/java/edu/uci/ics/genomix/pregelix/log/LogAlgorithmLogFormatter.java
@@ -16,7 +16,7 @@
     private VKmerBytesWritable sourceVertexId = new VKmerBytesWritable(1);
     private VKmerBytesWritable destVertexId = new VKmerBytesWritable(1);
     private LogAlgorithmMessageWritable msg = new LogAlgorithmMessageWritable();
-    private int state;
+    private byte state;
     private VKmerBytesWritable mergeChain = new VKmerBytesWritable(1);;
     //private boolean testDelete = false;
     /** 0: general operation 
@@ -30,7 +30,7 @@
     }
 
     public void set(long step, VKmerBytesWritable sourceVertexId, 
-    		VKmerBytesWritable destVertexId, LogAlgorithmMessageWritable msg, int state){
+    		VKmerBytesWritable destVertexId, LogAlgorithmMessageWritable msg, byte state){
     	this.step = step;
     	this.sourceVertexId.set(sourceVertexId);
     	this.destVertexId.set(destVertexId);
diff --git a/genomix/genomix-pregelix/src/main/java/edu/uci/ics/genomix/pregelix/operator/ThreeStepLogAlgorithmForPathMergeVertex.java b/genomix/genomix-pregelix/src/main/java/edu/uci/ics/genomix/pregelix/operator/ThreeStepLogAlgorithmForPathMergeVertex.java
index 1a1ef8a..70ba487 100644
--- a/genomix/genomix-pregelix/src/main/java/edu/uci/ics/genomix/pregelix/operator/ThreeStepLogAlgorithmForPathMergeVertex.java
+++ b/genomix/genomix-pregelix/src/main/java/edu/uci/ics/genomix/pregelix/operator/ThreeStepLogAlgorithmForPathMergeVertex.java
@@ -178,7 +178,8 @@
 			getVertexValue().setMergeChain(getVertexId());
 			setVertexValue(getVertexValue());
 		}
-		msg.set(msg.getSourceVertexId(), getVertexValue().getMergeChain(), getVertexValue().getAdjMap(), msg.getMessage(), getVertexValue().getState());
+		msg.set(null, getVertexValue().getMergeChain(), getVertexValue().getAdjMap(), msg.getMessage());
+		//msg.set(msg.getSourceVertexId(), getVertexValue().getMergeChain(), getVertexValue().getAdjMap(), msg.getMessage(), getVertexValue().getState());
 		setMessageType(msg.getMessage());
 		destVertexId.set(msg.getSourceVertexId());
 		sendMsg(destVertexId,msg);
@@ -240,12 +241,14 @@
 	 */
 	public void startSendMsg(){
 		if(GraphVertexOperation.isHeadVertex(getVertexValue().getAdjMap())){
-			msg.set(getVertexId(), chainVertexId, (byte)0, Message.START, State.NON_VERTEX); //msg.set(null, (byte)0, chainVertexId, Message.START, State.NON_VERTEX);
+			msg.set(null, null, (byte)0, Message.START);
+			//msg.set(getVertexId(), chainVertexId, (byte)0, Message.START, State.NON_VERTEX); //msg.set(null, (byte)0, chainVertexId, Message.START, State.NON_VERTEX);
 			sendMsgToAllNextNodes(getVertexId(), getVertexValue().getAdjMap());
 			voteToHalt();
 		}
 		if(GraphVertexOperation.isRearVertex(getVertexValue().getAdjMap())){
-			msg.set(getVertexId(), chainVertexId, (byte)0, Message.END, State.NON_VERTEX);
+			msg.set(null, null, (byte)0, Message.END);
+			//msg.set(getVertexId(), chainVertexId, (byte)0, Message.END, State.NON_VERTEX);
 			sendMsgToAllPreviousNodes(getVertexId(), getVertexValue().getAdjMap());
 			voteToHalt();
 		}
diff --git a/genomix/genomix-pregelix/src/main/java/edu/uci/ics/genomix/pregelix/operator/TwoStepLogAlgorithmForPathMergeVertex.java b/genomix/genomix-pregelix/src/main/java/edu/uci/ics/genomix/pregelix/operator/TwoStepLogAlgorithmForPathMergeVertex.java
index 526a57c..2bec590 100644
--- a/genomix/genomix-pregelix/src/main/java/edu/uci/ics/genomix/pregelix/operator/TwoStepLogAlgorithmForPathMergeVertex.java
+++ b/genomix/genomix-pregelix/src/main/java/edu/uci/ics/genomix/pregelix/operator/TwoStepLogAlgorithmForPathMergeVertex.java
@@ -132,6 +132,7 @@
 	 * send start message to next node
 	 */
 	public void sendStartMsgToNextNode(){
+		msg.reset();
 		msg.setMessage(Message.START);
 		msg.setSourceVertexId(getVertexId());
 		sendMsg(destVertexId, msg);
@@ -141,6 +142,7 @@
 	 * send end message to next node
 	 */
 	public void sendEndMsgToNextNode(){
+		msg.reset();
 		msg.setMessage(Message.END);
 		msg.setSourceVertexId(getVertexId());
 		sendMsg(destVertexId, msg);
@@ -179,9 +181,10 @@
 			getVertexValue().setMergeChain(getVertexId());
 			setVertexValue(getVertexValue());
 		}
-		msg.set(msg.getSourceVertexId(), getVertexValue().getMergeChain(), getVertexValue().getAdjMap(), msg.getMessage(), getVertexValue().getState());
-		setMessageType(msg.getMessage());
 		destVertexId.set(msg.getSourceVertexId());
+		msg.set(null, getVertexValue().getMergeChain(), getVertexValue().getAdjMap(), msg.getMessage());
+		//msg.set(msg.getSourceVertexId(), getVertexValue().getMergeChain(), getVertexValue().getAdjMap(), msg.getMessage(), getVertexValue().getState());
+		setMessageType(msg.getMessage());
 		sendMsg(destVertexId,msg);
 	}
 	/**
@@ -235,16 +238,18 @@
 		}
 	}
 	/**
-	 * start sending message
+	 * start sending message 
 	 */
 	public void startSendMsg(){
 		if(GraphVertexOperation.isHeadVertex(getVertexValue().getAdjMap())){
-			msg.set(getVertexId(), chainVertexId, (byte)0, Message.START, State.NON_VERTEX); //msg.set(null, (byte)0, chainVertexId, Message.START, State.NON_VERTEX);
+			msg.set(null, null, (byte)0, Message.START);
+			//msg.set(getVertexId(), chainVertexId, (byte)0, Message.START, State.NON_VERTEX); //msg.set(null, (byte)0, chainVertexId, Message.START, State.NON_VERTEX);
 			sendMsgToAllNextNodes(getVertexId(), getVertexValue().getAdjMap());
 			voteToHalt();
 		}
 		if(GraphVertexOperation.isRearVertex(getVertexValue().getAdjMap())){
-			msg.set(getVertexId(), chainVertexId, (byte)0, Message.END, State.NON_VERTEX);
+			msg.set(null, null, (byte)0, Message.END);
+			//msg.set(getVertexId(), chainVertexId, (byte)0, Message.END, State.NON_VERTEX);
 			sendMsgToAllPreviousNodes(getVertexId(), getVertexValue().getAdjMap());
 			voteToHalt();
 		}
@@ -273,7 +278,7 @@
 	 */
 	public void sendMsgToPathVertex(Iterator<LogAlgorithmMessageWritable> msgIterator){
 		if(getSuperstep() == 3){
-			msg.reset();
+			//msg.reset();
 			sendMsgToPathVertex(getVertexId(), getVertexValue().getAdjMap());
 		}
 		else{
diff --git a/genomix/genomix-pregelix/src/main/java/edu/uci/ics/genomix/pregelix/type/Message.java b/genomix/genomix-pregelix/src/main/java/edu/uci/ics/genomix/pregelix/type/Message.java
index f556a73..9e82cc9 100644
--- a/genomix/genomix-pregelix/src/main/java/edu/uci/ics/genomix/pregelix/type/Message.java
+++ b/genomix/genomix-pregelix/src/main/java/edu/uci/ics/genomix/pregelix/type/Message.java
@@ -2,13 +2,13 @@
 
 public class Message {
 	
-	public static final int NON = 0;
-	public static final int START = 1;
-	public static final int END = 2;
+	public static final byte NON = 0;
+	public static final byte START = 1;
+	public static final byte END = 2;
 	
 	public final static class MESSAGE_CONTENT{
 		
-		public static String getContentFromCode(int code){
+		public static String getContentFromCode(byte code){
 			String r = "";
 			switch(code){
 			case NON:
diff --git a/genomix/genomix-pregelix/src/main/java/edu/uci/ics/genomix/pregelix/type/State.java b/genomix/genomix-pregelix/src/main/java/edu/uci/ics/genomix/pregelix/type/State.java
index 61bcb0c..4bb40c9 100644
--- a/genomix/genomix-pregelix/src/main/java/edu/uci/ics/genomix/pregelix/type/State.java
+++ b/genomix/genomix-pregelix/src/main/java/edu/uci/ics/genomix/pregelix/type/State.java
@@ -1,18 +1,19 @@
 package edu.uci.ics.genomix.pregelix.type;
 
 public class State {
-	public static final int NON_VERTEX = 0;
-	public static final int START_VERTEX = 1;
-	public static final int END_VERTEX = 2;
-	public static final int MID_VERTEX = 3;
-	public static final int TODELETE = 4;
-	public static final int FINAL_VERTEX = 5;
-	public static final int FINAL_DELETE = 6;
-	public static final int KILL_SELF = 7;
+	
+	public static final byte NON_VERTEX = 0;
+	public static final byte START_VERTEX = 1;
+	public static final byte END_VERTEX = 2;
+	public static final byte MID_VERTEX = 3;
+	public static final byte TODELETE = 4;
+	public static final byte FINAL_VERTEX = 5;
+	public static final byte FINAL_DELETE = 6;
+	public static final byte KILL_SELF = 7;
 	
 	public final static class STATE_CONTENT{
 
-		public static String getContentFromCode(int code){
+		public static String getContentFromCode(byte code){
 			String r = "";
 			switch(code){
 			case NON_VERTEX:
diff --git a/genomix/genomix-pregelix/src/test/java/edu/uci/ics/genomix/pregelix/JobGen/JobGenerator.java b/genomix/genomix-pregelix/src/test/java/edu/uci/ics/genomix/pregelix/JobGen/JobGenerator.java
index d5b42c2..ea9da04 100644
--- a/genomix/genomix-pregelix/src/test/java/edu/uci/ics/genomix/pregelix/JobGen/JobGenerator.java
+++ b/genomix/genomix-pregelix/src/test/java/edu/uci/ics/genomix/pregelix/JobGen/JobGenerator.java
@@ -55,6 +55,7 @@
         FileInputFormat.setInputPaths(job, HDFS_INPUTPATH);
         FileOutputFormat.setOutputPath(job, new Path(HDFS_OUTPUTPAH));
         job.getConfiguration().setInt(NaiveAlgorithmForPathMergeVertex.KMER_SIZE, 5);
+        //job.getConfiguration().setInt(NaiveAlgorithmForPathMergeVertex.ITERATIONS, 10);
         job.getConfiguration().writeXml(new FileOutputStream(new File(outputPath)));
     }
     
@@ -73,6 +74,7 @@
         FileInputFormat.setInputPaths(job, HDFS_INPUTPATH);
         FileOutputFormat.setOutputPath(job, new Path(HDFS_OUTPUTPAH));
         job.getConfiguration().setInt(ThreeStepLogAlgorithmForPathMergeVertex.KMER_SIZE, 5);
+        job.getConfiguration().setInt(ThreeStepLogAlgorithmForPathMergeVertex.ITERATIONS, 5);
         job.getConfiguration().writeXml(new FileOutputStream(new File(outputPath)));
     }
     
@@ -105,8 +107,8 @@
 	public static void main(String[] args) throws IOException {
 		// TODO Auto-generated method stub
 		//genLoadGraph();
-		//genMergeGraph();
-		genThreeStepLogAlgorithmForMergeGraph();
+		genMergeGraph();
+		//genThreeStepLogAlgorithmForMergeGraph();
 		//genTwoStepLogAlgorithmForMergeGraph();
 	}
 
diff --git a/genomix/genomix-pregelix/src/test/java/edu/uci/ics/genomix/pregelix/JobRun/RunJobTestSuite.java b/genomix/genomix-pregelix/src/test/java/edu/uci/ics/genomix/pregelix/JobRun/RunJobTestSuite.java
index 45d8185..fd0749a 100644
--- a/genomix/genomix-pregelix/src/test/java/edu/uci/ics/genomix/pregelix/JobRun/RunJobTestSuite.java
+++ b/genomix/genomix-pregelix/src/test/java/edu/uci/ics/genomix/pregelix/JobRun/RunJobTestSuite.java
@@ -40,7 +40,7 @@
 	private static final String PATH_TO_ONLY = "src/test/resources/only.txt";
 	private static final String FILE_EXTENSION_OF_RESULTS = "result";
 
-	private static final String DATA_PATH = "data/sequencefile/TreePath";
+	private static final String DATA_PATH = "data/sequencefile/LongPath";
 	private static final String HDFS_PATH = "/webmap/";
 
 	private static final String HYRACKS_APP_NAME = "pregelix";