diff --git a/pregelix/pregelix-dataflow/src/main/java/edu/uci/ics/pregelix/dataflow/context/PreDelayPageCleanerPolicy.java b/pregelix/pregelix-dataflow/src/main/java/edu/uci/ics/pregelix/dataflow/context/PreDelayPageCleanerPolicy.java
new file mode 100644
index 0000000..2b07c81
--- /dev/null
+++ b/pregelix/pregelix-dataflow/src/main/java/edu/uci/ics/pregelix/dataflow/context/PreDelayPageCleanerPolicy.java
@@ -0,0 +1,46 @@
+/*
+ * Copyright 2009-2010 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.dataflow.context;
+
+import edu.uci.ics.hyracks.api.exceptions.HyracksDataException;
+import edu.uci.ics.hyracks.storage.common.buffercache.IPageCleanerPolicy;
+
+public class PreDelayPageCleanerPolicy implements IPageCleanerPolicy {
+    private long delay;
+
+    public PreDelayPageCleanerPolicy(long delay) {
+        this.delay = delay;
+    }
+
+    @Override
+    public void notifyCleanCycleStart(Object monitor) throws HyracksDataException {
+        try {
+            monitor.wait(delay);
+        } catch (InterruptedException e) {
+            throw new HyracksDataException(e);
+        }
+    }
+
+    @Override
+    public void notifyCleanCycleFinish(Object monitor) throws HyracksDataException {
+       
+    }
+
+    @Override
+    public void notifyVictimNotFound(Object monitor) throws HyracksDataException {
+        monitor.notifyAll();
+    }
+}
diff --git a/pregelix/pregelix-dataflow/src/main/java/edu/uci/ics/pregelix/dataflow/context/RuntimeContext.java b/pregelix/pregelix-dataflow/src/main/java/edu/uci/ics/pregelix/dataflow/context/RuntimeContext.java
index cb76637..43b6d17 100644
--- a/pregelix/pregelix-dataflow/src/main/java/edu/uci/ics/pregelix/dataflow/context/RuntimeContext.java
+++ b/pregelix/pregelix-dataflow/src/main/java/edu/uci/ics/pregelix/dataflow/context/RuntimeContext.java
@@ -32,7 +32,6 @@
 import edu.uci.ics.hyracks.storage.am.common.dataflow.IndexRegistry;
 import edu.uci.ics.hyracks.storage.common.buffercache.BufferCache;
 import edu.uci.ics.hyracks.storage.common.buffercache.ClockPageReplacementStrategy;
-import edu.uci.ics.hyracks.storage.common.buffercache.DelayPageCleanerPolicy;
 import edu.uci.ics.hyracks.storage.common.buffercache.HeapBufferAllocator;
 import edu.uci.ics.hyracks.storage.common.buffercache.IBufferCache;
 import edu.uci.ics.hyracks.storage.common.buffercache.ICacheMemoryAllocator;
@@ -62,8 +61,9 @@
         long memSize = Runtime.getRuntime().maxMemory();
         long bufferSize = memSize / 4;
         int numPages = (int) (bufferSize / pageSize);
+        /** let the buffer cache never flush dirty pages */
         bufferCache = new BufferCache(appCtx.getRootContext().getIOManager(), allocator, prs,
-                new DelayPageCleanerPolicy(100000), fileMapManager, pageSize, numPages, 1000000);
+                new PreDelayPageCleanerPolicy(Long.MAX_VALUE), fileMapManager, pageSize, numPages, 1000000);
         treeIndexRegistry = new IndexRegistry<IIndex>();
         ioManager = (IOManager) appCtx.getRootContext().getIOManager();
     }