diff --git a/pregelix-example/pom.xml b/pregelix-example/pom.xml
index 1066e3b..9994c0e 100644
--- a/pregelix-example/pom.xml
+++ b/pregelix-example/pom.xml
@@ -94,7 +94,7 @@
 			<plugin>
 				<groupId>org.apache.maven.plugins</groupId>
 				<artifactId>maven-clean-plugin</artifactId>
-				<version>2.4.1</version>
+				<version>2.5</version>
 				<configuration>
 					<filesets>
 						<fileset>
diff --git a/pregelix-example/src/test/java/edu/uci/ics/pregelix/example/FailureRecoveryTest.java b/pregelix-example/src/test/java/edu/uci/ics/pregelix/example/FailureRecoveryTest.java
new file mode 100644
index 0000000..dac087f
--- /dev/null
+++ b/pregelix-example/src/test/java/edu/uci/ics/pregelix/example/FailureRecoveryTest.java
@@ -0,0 +1,86 @@
+/*
+ * Copyright 2009-2013 by The Regents of the University of California
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * you may obtain a copy of the License from
+ * 
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ * 
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package edu.uci.ics.pregelix.example;
+
+import java.io.File;
+
+import org.apache.hadoop.fs.Path;
+import org.apache.hadoop.mapreduce.lib.input.FileInputFormat;
+import org.apache.hadoop.mapreduce.lib.output.FileOutputFormat;
+import org.junit.Test;
+
+import edu.uci.ics.pregelix.api.job.PregelixJob;
+import edu.uci.ics.pregelix.api.util.ConservativeCheckpointHook;
+import edu.uci.ics.pregelix.core.driver.Driver;
+import edu.uci.ics.pregelix.core.util.PregelixHyracksIntegrationUtil;
+import edu.uci.ics.pregelix.example.PageRankVertex.SimplePageRankVertexOutputFormat;
+import edu.uci.ics.pregelix.example.data.VLongNormalizedKeyComputer;
+import edu.uci.ics.pregelix.example.inputformat.TextPageRankInputFormat;
+import edu.uci.ics.pregelix.example.util.TestCluster;
+import edu.uci.ics.pregelix.example.util.TestUtils;
+
+/**
+ * @author yingyib
+ */
+public class FailureRecoveryTest {
+    private static String INPUTPATH = "data/webmap";
+    private static String OUTPUTPAH = "actual/result";
+    private static String EXPECTEDPATH = "src/test/resources/expected/PageRankReal";
+
+    @Test
+    public void test() throws Exception {
+        TestCluster testCluster = new TestCluster();
+
+        try {
+            PregelixJob job = new PregelixJob(PageRankVertex.class.getName());
+            job.setVertexClass(PageRankVertex.class);
+            job.setVertexInputFormatClass(TextPageRankInputFormat.class);
+            job.setVertexOutputFormatClass(SimplePageRankVertexOutputFormat.class);
+            job.setMessageCombinerClass(PageRankVertex.SimpleSumCombiner.class);
+            job.setNoramlizedKeyComputerClass(VLongNormalizedKeyComputer.class);
+            FileInputFormat.setInputPaths(job, INPUTPATH);
+            FileOutputFormat.setOutputPath(job, new Path(OUTPUTPAH));
+            job.getConfiguration().setLong(PregelixJob.NUM_VERTICE, 20);
+            job.setCheckpointHook(ConservativeCheckpointHook.class);
+
+            testCluster.setUp();
+            Driver driver = new Driver(PageRankVertex.class);
+            //            Thread thread = new Thread(new Runnable() {
+            //
+            //                @Override
+            //                public void run() {
+            //                    try {
+            //                        synchronized (this) {
+            //                            this.wait(10000);
+            //                            PregelixHyracksIntegrationUtil.showDownNC1();
+            //                        }
+            //                    } catch (Exception e) {
+            //                        throw new IllegalStateException(e);
+            //                    }
+            //                }
+            //
+            //            });
+            //thread.start();
+            driver.runJob(job, "127.0.0.1", PregelixHyracksIntegrationUtil.TEST_HYRACKS_CC_CLIENT_PORT);
+
+            TestUtils.compareWithResultDir(new File(EXPECTEDPATH), new File(OUTPUTPAH));
+        } catch (Exception e) {
+            throw e;
+        } finally {
+            testCluster.tearDown();
+        }
+    }
+
+}
diff --git a/pregelix-example/src/test/java/edu/uci/ics/pregelix/example/test/FailureVertexTest.java b/pregelix-example/src/test/java/edu/uci/ics/pregelix/example/FailureVertexTest.java
similarity index 96%
rename from pregelix-example/src/test/java/edu/uci/ics/pregelix/example/test/FailureVertexTest.java
rename to pregelix-example/src/test/java/edu/uci/ics/pregelix/example/FailureVertexTest.java
index 5a2636a..a2d32c0 100644
--- a/pregelix-example/src/test/java/edu/uci/ics/pregelix/example/test/FailureVertexTest.java
+++ b/pregelix-example/src/test/java/edu/uci/ics/pregelix/example/FailureVertexTest.java
@@ -12,7 +12,7 @@
  * See the License for the specific language governing permissions and
  * limitations under the License.
  */
-package edu.uci.ics.pregelix.example.test;
+package edu.uci.ics.pregelix.example;
 
 import junit.framework.Assert;
 
@@ -29,6 +29,7 @@
 import edu.uci.ics.pregelix.example.FailureVertex;
 import edu.uci.ics.pregelix.example.data.VLongNormalizedKeyComputer;
 import edu.uci.ics.pregelix.example.inputformat.TextPageRankInputFormat;
+import edu.uci.ics.pregelix.example.util.TestCluster;
 
 /**
  * This test case tests the error message propagation.
diff --git a/pregelix-example/src/test/java/edu/uci/ics/pregelix/example/test/JobConcatenationTest.java b/pregelix-example/src/test/java/edu/uci/ics/pregelix/example/JobConcatenationTest.java
similarity index 91%
rename from pregelix-example/src/test/java/edu/uci/ics/pregelix/example/test/JobConcatenationTest.java
rename to pregelix-example/src/test/java/edu/uci/ics/pregelix/example/JobConcatenationTest.java
index d2995f1..5a485ba 100644
--- a/pregelix-example/src/test/java/edu/uci/ics/pregelix/example/test/JobConcatenationTest.java
+++ b/pregelix-example/src/test/java/edu/uci/ics/pregelix/example/JobConcatenationTest.java
@@ -12,7 +12,7 @@
  * See the License for the specific language governing permissions and
  * limitations under the License.
  */
-package edu.uci.ics.pregelix.example.test;
+package edu.uci.ics.pregelix.example;
 
 import java.io.File;
 import java.util.ArrayList;
@@ -24,13 +24,12 @@
 import org.junit.Test;
 
 import edu.uci.ics.pregelix.api.job.PregelixJob;
-import edu.uci.ics.pregelix.api.util.ConservativeCheckpointHook;
 import edu.uci.ics.pregelix.core.driver.Driver;
 import edu.uci.ics.pregelix.core.util.PregelixHyracksIntegrationUtil;
-import edu.uci.ics.pregelix.example.PageRankVertex;
 import edu.uci.ics.pregelix.example.PageRankVertex.SimplePageRankVertexOutputFormat;
 import edu.uci.ics.pregelix.example.data.VLongNormalizedKeyComputer;
 import edu.uci.ics.pregelix.example.inputformat.TextPageRankInputFormat;
+import edu.uci.ics.pregelix.example.util.TestCluster;
 import edu.uci.ics.pregelix.example.util.TestUtils;
 
 /**
@@ -56,7 +55,7 @@
             job1.setNoramlizedKeyComputerClass(VLongNormalizedKeyComputer.class);
             FileInputFormat.setInputPaths(job1, INPUTPATH);
             job1.getConfiguration().setLong(PregelixJob.NUM_VERTICE, 20);
-            job1.setCheckpointHook(ConservativeCheckpointHook.class);
+            //job1.setCheckpointHook(ConservativeCheckpointHook.class);
 
             PregelixJob job2 = new PregelixJob(PageRankVertex.class.getName());
             job2.setVertexClass(PageRankVertex.class);
@@ -66,7 +65,7 @@
             job2.setNoramlizedKeyComputerClass(VLongNormalizedKeyComputer.class);
             FileOutputFormat.setOutputPath(job2, new Path(OUTPUTPAH));
             job2.getConfiguration().setLong(PregelixJob.NUM_VERTICE, 20);
-            job2.setCheckpointHook(ConservativeCheckpointHook.class);
+            //job2.setCheckpointHook(ConservativeCheckpointHook.class);
 
             jobs.add(job1);
             jobs.add(job2);
diff --git a/pregelix-example/src/test/java/edu/uci/ics/pregelix/example/OverflowAggregatorTest.java b/pregelix-example/src/test/java/edu/uci/ics/pregelix/example/OverflowAggregatorTest.java
new file mode 100644
index 0000000..474d0a6
--- /dev/null
+++ b/pregelix-example/src/test/java/edu/uci/ics/pregelix/example/OverflowAggregatorTest.java
@@ -0,0 +1,79 @@
+/*
+ * Copyright 2009-2013 by The Regents of the University of California
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * you may obtain a copy of the License from
+ * 
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ * 
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package edu.uci.ics.pregelix.example;
+
+import java.io.File;
+
+import junit.framework.Assert;
+
+import org.apache.hadoop.fs.Path;
+import org.apache.hadoop.io.Text;
+import org.apache.hadoop.mapreduce.lib.input.FileInputFormat;
+import org.apache.hadoop.mapreduce.lib.output.FileOutputFormat;
+import org.junit.Test;
+
+import edu.uci.ics.pregelix.api.job.PregelixJob;
+import edu.uci.ics.pregelix.api.util.BspUtils;
+import edu.uci.ics.pregelix.core.driver.Driver;
+import edu.uci.ics.pregelix.core.util.PregelixHyracksIntegrationUtil;
+import edu.uci.ics.pregelix.dataflow.util.IterationUtils;
+import edu.uci.ics.pregelix.example.PageRankVertex.SimplePageRankVertexOutputFormat;
+import edu.uci.ics.pregelix.example.aggregator.OverflowAggregator;
+import edu.uci.ics.pregelix.example.data.VLongNormalizedKeyComputer;
+import edu.uci.ics.pregelix.example.inputformat.TextPageRankInputFormat;
+import edu.uci.ics.pregelix.example.util.TestCluster;
+import edu.uci.ics.pregelix.example.util.TestUtils;
+
+/**
+ * @author yingyib
+ */
+public class OverflowAggregatorTest {
+
+    private static String INPUTPATH = "data/webmap";
+    private static String OUTPUTPAH = "actual/result";
+    private static String EXPECTEDPATH = "src/test/resources/expected/PageRankReal";
+
+    @Test
+    public void test() throws Exception {
+        TestCluster testCluster = new TestCluster();
+
+        try {
+            PregelixJob job = new PregelixJob(PageRankVertex.class.getName());
+            job.setVertexClass(PageRankVertex.class);
+            job.setVertexInputFormatClass(TextPageRankInputFormat.class);
+            job.setVertexOutputFormatClass(SimplePageRankVertexOutputFormat.class);
+            job.setMessageCombinerClass(PageRankVertex.SimpleSumCombiner.class);
+            job.setNoramlizedKeyComputerClass(VLongNormalizedKeyComputer.class);
+            FileInputFormat.setInputPaths(job, INPUTPATH);
+            FileOutputFormat.setOutputPath(job, new Path(OUTPUTPAH));
+            job.getConfiguration().setLong(PregelixJob.NUM_VERTICE, 20);
+            job.setGlobalAggregatorClass(OverflowAggregator.class);
+
+            testCluster.setUp();
+            Driver driver = new Driver(PageRankVertex.class);
+            driver.runJob(job, "127.0.0.1", PregelixHyracksIntegrationUtil.TEST_HYRACKS_CC_CLIENT_PORT);
+
+            TestUtils.compareWithResultDir(new File(EXPECTEDPATH), new File(OUTPUTPAH));
+            Text text = (Text) IterationUtils.readGlobalAggregateValue(job.getConfiguration(),
+                    BspUtils.getJobId(job.getConfiguration()));
+            Assert.assertEquals(text.getLength(), 20 * 32767);
+        } catch (Exception e) {
+            throw e;
+        } finally {
+            testCluster.tearDown();
+        }
+    }
+
+}
diff --git a/pregelix-example/src/test/java/edu/uci/ics/pregelix/example/aggregator/OverflowAggregator.java b/pregelix-example/src/test/java/edu/uci/ics/pregelix/example/aggregator/OverflowAggregator.java
new file mode 100644
index 0000000..34b8b51
--- /dev/null
+++ b/pregelix-example/src/test/java/edu/uci/ics/pregelix/example/aggregator/OverflowAggregator.java
@@ -0,0 +1,75 @@
+/*
+ * Copyright 2009-2013 by The Regents of the University of California
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * you may obtain a copy of the License from
+ * 
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ * 
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package edu.uci.ics.pregelix.example.aggregator;
+
+import org.apache.hadoop.io.FloatWritable;
+import org.apache.hadoop.io.Text;
+
+import edu.uci.ics.hyracks.api.exceptions.HyracksDataException;
+import edu.uci.ics.pregelix.api.graph.GlobalAggregator;
+import edu.uci.ics.pregelix.api.graph.Vertex;
+import edu.uci.ics.pregelix.example.io.DoubleWritable;
+import edu.uci.ics.pregelix.example.io.VLongWritable;
+
+/**
+ * Test the case where the global aggregate's state is bloated
+ * 
+ * @author yingyib
+ */
+public class OverflowAggregator extends
+        GlobalAggregator<VLongWritable, DoubleWritable, FloatWritable, DoubleWritable, Text, Text> {
+
+    private int textLength = 0;
+    private int inc = 32767;
+
+    @Override
+    public void init() {
+        textLength = 0;
+    }
+
+    @Override
+    public void step(Vertex<VLongWritable, DoubleWritable, FloatWritable, DoubleWritable> v)
+            throws HyracksDataException {
+        textLength += inc;
+    }
+
+    @Override
+    public void step(Text partialResult) {
+        textLength += partialResult.getLength();
+    }
+
+    @Override
+    public Text finishPartial() {
+        byte[] partialResult = new byte[textLength];
+        for (int i = 0; i < partialResult.length; i++) {
+            partialResult[i] = 'a';
+        }
+        Text text = new Text();
+        text.set(partialResult);
+        return text;
+    }
+
+    @Override
+    public Text finishFinal() {
+        byte[] result = new byte[textLength];
+        for (int i = 0; i < result.length; i++) {
+            result[i] = 'a';
+        }
+        Text text = new Text();
+        text.set(result);
+        return text;
+    }
+
+}
diff --git a/pregelix-example/src/test/java/edu/uci/ics/pregelix/example/test/TestCluster.java b/pregelix-example/src/test/java/edu/uci/ics/pregelix/example/util/TestCluster.java
similarity index 98%
rename from pregelix-example/src/test/java/edu/uci/ics/pregelix/example/test/TestCluster.java
rename to pregelix-example/src/test/java/edu/uci/ics/pregelix/example/util/TestCluster.java
index d0cf654..40ea690 100644
--- a/pregelix-example/src/test/java/edu/uci/ics/pregelix/example/test/TestCluster.java
+++ b/pregelix-example/src/test/java/edu/uci/ics/pregelix/example/util/TestCluster.java
@@ -12,7 +12,7 @@
  * See the License for the specific language governing permissions and
  * limitations under the License.
  */
-package edu.uci.ics.pregelix.example.test;
+package edu.uci.ics.pregelix.example.util;
 
 import java.io.BufferedReader;
 import java.io.DataOutputStream;