diff --git a/hyracks/hyracks-api/src/main/java/edu/uci/ics/hyracks/api/client/impl/JobSpecificationActivityClusterGraphGeneratorFactory.java b/hyracks/hyracks-api/src/main/java/edu/uci/ics/hyracks/api/client/impl/JobSpecificationActivityClusterGraphGeneratorFactory.java
index 91a39d7..0eac9a2 100644
--- a/hyracks/hyracks-api/src/main/java/edu/uci/ics/hyracks/api/client/impl/JobSpecificationActivityClusterGraphGeneratorFactory.java
+++ b/hyracks/hyracks-api/src/main/java/edu/uci/ics/hyracks/api/client/impl/JobSpecificationActivityClusterGraphGeneratorFactory.java
@@ -23,7 +23,6 @@
     private static final long serialVersionUID = 1L;
 
     private final JobSpecification spec;
-    private final ActivityClusterGraphRewriter rewriter = new ActivityClusterGraphRewriter();
 
     public JobSpecificationActivityClusterGraphGeneratorFactory(JobSpecification jobSpec) {
         this.spec = jobSpec;
@@ -80,6 +79,7 @@
         return new IActivityClusterGraphGenerator() {
             @Override
             public ActivityClusterGraph initialize() {
+                ActivityClusterGraphRewriter rewriter = new ActivityClusterGraphRewriter();
                 rewriter.rewrite(acg);
                 return acg;
             }
diff --git a/hyracks/hyracks-api/src/main/java/edu/uci/ics/hyracks/api/rewriter/ActivityClusterGraphRewriter.java b/hyracks/hyracks-api/src/main/java/edu/uci/ics/hyracks/api/rewriter/ActivityClusterGraphRewriter.java
index f1aee37..6f5f74b 100644
--- a/hyracks/hyracks-api/src/main/java/edu/uci/ics/hyracks/api/rewriter/ActivityClusterGraphRewriter.java
+++ b/hyracks/hyracks-api/src/main/java/edu/uci/ics/hyracks/api/rewriter/ActivityClusterGraphRewriter.java
@@ -15,7 +15,6 @@
 
 package edu.uci.ics.hyracks.api.rewriter;
 
-import java.io.Serializable;
 import java.util.HashMap;
 import java.util.HashSet;
 import java.util.LinkedList;
@@ -46,8 +45,7 @@
  * 
  * @author yingyib
  */
-public class ActivityClusterGraphRewriter implements Serializable {
-    private static final long serialVersionUID = 1L;
+public class ActivityClusterGraphRewriter {
     private static String ONE_TO_ONE_CONNECTOR = "OneToOneConnectorDescriptor";
 
     /**