diff --git a/hadoop-common-project/hadoop-common/src/main/java/org/apache/hadoop/util/HostsFileReader.java b/hadoop-common-project/hadoop-common/src/main/java/org/apache/hadoop/util/HostsFileReader.java
index cac43c90e5b..c5d6b869c35 100644
--- a/hadoop-common-project/hadoop-common/src/main/java/org/apache/hadoop/util/HostsFileReader.java
+++ b/hadoop-common-project/hadoop-common/src/main/java/org/apache/hadoop/util/HostsFileReader.java
@@ -21,6 +21,9 @@ package org.apache.hadoop.util;
 import java.io.*;
 import java.util.Set;
 import java.util.HashSet;
+import java.util.concurrent.locks.ReentrantReadWriteLock;
+import java.util.concurrent.locks.ReentrantReadWriteLock.ReadLock;
+import java.util.concurrent.locks.ReentrantReadWriteLock.WriteLock;
 
 import org.apache.commons.io.Charsets;
 import org.apache.commons.logging.LogFactory;
@@ -38,6 +41,8 @@ public class HostsFileReader {
   private Set<String> excludes;
   private String includesFile;
   private String excludesFile;
+  private WriteLock writeLock;
+  private ReadLock readLock;
   
   private static final Log LOG = LogFactory.getLog(HostsFileReader.class);
 
@@ -47,6 +52,9 @@ public class HostsFileReader {
     excludes = new HashSet<String>();
     includesFile = inFile;
     excludesFile = exFile;
+    ReentrantReadWriteLock rwLock = new ReentrantReadWriteLock();
+    this.writeLock = rwLock.writeLock();
+    this.readLock = rwLock.readLock();
     refresh();
   }
 
@@ -57,6 +65,9 @@ public class HostsFileReader {
     excludes = new HashSet<String>();
     this.includesFile = includesFile;
     this.excludesFile = excludesFile;
+    ReentrantReadWriteLock rwLock = new ReentrantReadWriteLock();
+    this.writeLock = rwLock.writeLock();
+    this.readLock = rwLock.readLock();
     refresh(inFileInputStream, exFileInputStream);
   }
 
@@ -101,80 +112,126 @@ public class HostsFileReader {
     }
   }
 
-  public synchronized void refresh() throws IOException {
-    LOG.info("Refreshing hosts (include/exclude) list");
-    Set<String> newIncludes = new HashSet<String>();
-    Set<String> newExcludes = new HashSet<String>();
-    boolean switchIncludes = false;
-    boolean switchExcludes = false;
-    if (!includesFile.isEmpty()) {
-      readFileToSet("included", includesFile, newIncludes);
-      switchIncludes = true;
-    }
-    if (!excludesFile.isEmpty()) {
-      readFileToSet("excluded", excludesFile, newExcludes);
-      switchExcludes = true;
+  public void refresh() throws IOException {
+    this.writeLock.lock();
+    try {
+      refresh(includesFile, excludesFile);
+    } finally {
+      this.writeLock.unlock();
     }
+  }
 
-    if (switchIncludes) {
-      // switch the new hosts that are to be included
-      includes = newIncludes;
-    }
-    if (switchExcludes) {
-      // switch the excluded hosts
-      excludes = newExcludes;
+  public void refresh(String includeFiles, String excludeFiles)
+      throws IOException {
+    LOG.info("Refreshing hosts (include/exclude) list");
+    this.writeLock.lock();
+    try {
+      // update instance variables
+      updateFileNames(includeFiles, excludeFiles);
+      Set<String> newIncludes = new HashSet<String>();
+      Set<String> newExcludes = new HashSet<String>();
+      boolean switchIncludes = false;
+      boolean switchExcludes = false;
+      if (includeFiles != null && !includeFiles.isEmpty()) {
+        readFileToSet("included", includeFiles, newIncludes);
+        switchIncludes = true;
+      }
+      if (excludeFiles != null && !excludeFiles.isEmpty()) {
+        readFileToSet("excluded", excludeFiles, newExcludes);
+        switchExcludes = true;
+      }
+
+      if (switchIncludes) {
+        // switch the new hosts that are to be included
+        includes = newIncludes;
+      }
+      if (switchExcludes) {
+        // switch the excluded hosts
+        excludes = newExcludes;
+      }
+    } finally {
+      this.writeLock.unlock();
     }
   }
 
   @Private
-  public synchronized void refresh(InputStream inFileInputStream,
+  public void refresh(InputStream inFileInputStream,
       InputStream exFileInputStream) throws IOException {
     LOG.info("Refreshing hosts (include/exclude) list");
-    Set<String> newIncludes = new HashSet<String>();
-    Set<String> newExcludes = new HashSet<String>();
-    boolean switchIncludes = false;
-    boolean switchExcludes = false;
-    if (inFileInputStream != null) {
-      readFileToSetWithFileInputStream("included", includesFile,
-          inFileInputStream, newIncludes);
-      switchIncludes = true;
-    }
-    if (exFileInputStream != null) {
-      readFileToSetWithFileInputStream("excluded", excludesFile,
-          exFileInputStream, newExcludes);
-      switchExcludes = true;
-    }
-    if (switchIncludes) {
-      // switch the new hosts that are to be included
-      includes = newIncludes;
-    }
-    if (switchExcludes) {
-      // switch the excluded hosts
-      excludes = newExcludes;
+    this.writeLock.lock();
+    try {
+      Set<String> newIncludes = new HashSet<String>();
+      Set<String> newExcludes = new HashSet<String>();
+      boolean switchIncludes = false;
+      boolean switchExcludes = false;
+      if (inFileInputStream != null) {
+        readFileToSetWithFileInputStream("included", includesFile,
+            inFileInputStream, newIncludes);
+        switchIncludes = true;
+      }
+      if (exFileInputStream != null) {
+        readFileToSetWithFileInputStream("excluded", excludesFile,
+            exFileInputStream, newExcludes);
+        switchExcludes = true;
+      }
+      if (switchIncludes) {
+        // switch the new hosts that are to be included
+        includes = newIncludes;
+      }
+      if (switchExcludes) {
+        // switch the excluded hosts
+        excludes = newExcludes;
+      }
+    } finally {
+      this.writeLock.unlock();
     }
   }
 
-  public synchronized Set<String> getHosts() {
-    return includes;
+  public Set<String> getHosts() {
+    this.readLock.lock();
+    try {
+      return includes;
+    } finally {
+      this.readLock.unlock();
+    }
   }
 
-  public synchronized Set<String> getExcludedHosts() {
-    return excludes;
+  public Set<String> getExcludedHosts() {
+    this.readLock.lock();
+    try {
+      return excludes;
+    } finally {
+      this.readLock.unlock();
+    }
   }
 
-  public synchronized void setIncludesFile(String includesFile) {
+  public void getHostDetails(Set<String> includes, Set<String> excludes) {
+    this.readLock.lock();
+    try {
+      includes.addAll(this.includes);
+      excludes.addAll(this.excludes);
+    } finally {
+      this.readLock.unlock();
+    }
+  }
+
+  public void setIncludesFile(String includesFile) {
     LOG.info("Setting the includes file to " + includesFile);
     this.includesFile = includesFile;
   }
   
-  public synchronized void setExcludesFile(String excludesFile) {
+  public void setExcludesFile(String excludesFile) {
     LOG.info("Setting the excludes file to " + excludesFile);
     this.excludesFile = excludesFile;
   }
 
-  public synchronized void updateFileNames(String includesFile,
-      String excludesFile) {
-    setIncludesFile(includesFile);
-    setExcludesFile(excludesFile);
+  public void updateFileNames(String includeFiles, String excludeFiles) {
+    this.writeLock.lock();
+    try {
+      setIncludesFile(includeFiles);
+      setExcludesFile(excludeFiles);
+    } finally {
+      this.writeLock.unlock();
+    }
   }
 }
diff --git a/hadoop-common-project/hadoop-common/src/test/java/org/apache/hadoop/util/TestHostsFileReader.java b/hadoop-common-project/hadoop-common/src/test/java/org/apache/hadoop/util/TestHostsFileReader.java
index 7de0be859f7..b1c5825d23a 100644
--- a/hadoop-common-project/hadoop-common/src/test/java/org/apache/hadoop/util/TestHostsFileReader.java
+++ b/hadoop-common-project/hadoop-common/src/test/java/org/apache/hadoop/util/TestHostsFileReader.java
@@ -20,6 +20,8 @@ package org.apache.hadoop.util;
 import java.io.File;
 import java.io.FileNotFoundException;
 import java.io.FileWriter;
+import java.util.HashSet;
+import java.util.Set;
 
 import org.junit.*;
 import static org.junit.Assert.*;
@@ -96,6 +98,30 @@ public class TestHostsFileReader {
     assertTrue(hfp.getExcludedHosts().contains("somehost5"));
     assertFalse(hfp.getExcludedHosts().contains("host4"));
 
+    // test for refreshing hostreader wit new include/exclude host files
+    String newExcludesFile = HOSTS_TEST_DIR + "/dfs1.exclude";
+    String newIncludesFile = HOSTS_TEST_DIR + "/dfs1.include";
+
+    efw = new FileWriter(newExcludesFile);
+    ifw = new FileWriter(newIncludesFile);
+
+    efw.write("#DFS-Hosts-excluded\n");
+    efw.write("node1\n");
+    efw.close();
+
+    ifw.write("#Hosts-in-DFS\n");
+    ifw.write("node2\n");
+    ifw.close();
+
+    hfp.refresh(newIncludesFile, newExcludesFile);
+    assertTrue(hfp.getExcludedHosts().contains("node1"));
+    assertTrue(hfp.getHosts().contains("node2"));
+
+    Set<String> hostsList = new HashSet<String>();
+    Set<String> excludeList = new HashSet<String>();
+    hfp.getHostDetails(hostsList, excludeList);
+    assertTrue(excludeList.contains("node1"));
+    assertTrue(hostsList.contains("node2"));
   }
 
   /*
diff --git a/hadoop-yarn-project/hadoop-yarn/hadoop-yarn-server/hadoop-yarn-server-resourcemanager/src/main/java/org/apache/hadoop/yarn/server/resourcemanager/NodesListManager.java b/hadoop-yarn-project/hadoop-yarn/hadoop-yarn-server/hadoop-yarn-server-resourcemanager/src/main/java/org/apache/hadoop/yarn/server/resourcemanager/NodesListManager.java
index a093540c090..e69db296e62 100644
--- a/hadoop-yarn-project/hadoop-yarn/hadoop-yarn-server/hadoop-yarn-server-resourcemanager/src/main/java/org/apache/hadoop/yarn/server/resourcemanager/NodesListManager.java
+++ b/hadoop-yarn-project/hadoop-yarn/hadoop-yarn-server/hadoop-yarn-server-resourcemanager/src/main/java/org/apache/hadoop/yarn/server/resourcemanager/NodesListManager.java
@@ -182,10 +182,15 @@ public class NodesListManager extends CompositeService implements
         YarnConfiguration.DEFAULT_RM_NODES_INCLUDE_FILE_PATH) + " out=" +
         conf.get(YarnConfiguration.RM_NODES_EXCLUDE_FILE_PATH, 
             YarnConfiguration.DEFAULT_RM_NODES_EXCLUDE_FILE_PATH));
-    for (String include : hostsReader.getHosts()) {
+
+    Set<String> hostsList = new HashSet<String>();
+    Set<String> excludeList = new HashSet<String>();
+    hostsReader.getHostDetails(hostsList, excludeList);
+
+    for (String include : hostsList) {
       LOG.debug("include: " + include);
     }
-    for (String exclude : hostsReader.getExcludedHosts()) {
+    for (String exclude : excludeList) {
       LOG.debug("exclude: " + exclude);
     }
   }
@@ -207,25 +212,17 @@ public class NodesListManager extends CompositeService implements
 
   private void refreshHostsReader(Configuration yarnConf) throws IOException,
       YarnException {
-    synchronized (hostsReader) {
-      if (null == yarnConf) {
-        yarnConf = new YarnConfiguration();
-      }
-      includesFile =
-          yarnConf.get(YarnConfiguration.RM_NODES_INCLUDE_FILE_PATH,
-              YarnConfiguration.DEFAULT_RM_NODES_INCLUDE_FILE_PATH);
-      excludesFile =
-          yarnConf.get(YarnConfiguration.RM_NODES_EXCLUDE_FILE_PATH,
-              YarnConfiguration.DEFAULT_RM_NODES_EXCLUDE_FILE_PATH);
-      hostsReader.updateFileNames(includesFile, excludesFile);
-      hostsReader.refresh(
-          includesFile.isEmpty() ? null : this.rmContext
-              .getConfigurationProvider().getConfigurationInputStream(
-                  this.conf, includesFile), excludesFile.isEmpty() ? null
-              : this.rmContext.getConfigurationProvider()
-                  .getConfigurationInputStream(this.conf, excludesFile));
-      printConfiguredHosts();
+    if (null == yarnConf) {
+      yarnConf = new YarnConfiguration();
     }
+    includesFile =
+        yarnConf.get(YarnConfiguration.RM_NODES_INCLUDE_FILE_PATH,
+            YarnConfiguration.DEFAULT_RM_NODES_INCLUDE_FILE_PATH);
+    excludesFile =
+        yarnConf.get(YarnConfiguration.RM_NODES_EXCLUDE_FILE_PATH,
+            YarnConfiguration.DEFAULT_RM_NODES_EXCLUDE_FILE_PATH);
+    hostsReader.refresh(includesFile, excludesFile);
+    printConfiguredHosts();
   }
 
   private void setDecomissionedNMs() {
@@ -363,13 +360,13 @@ public class NodesListManager extends CompositeService implements
 
   public boolean isValidNode(String hostName) {
     String ip = resolver.resolve(hostName);
-    synchronized (hostsReader) {
-      Set<String> hostsList = hostsReader.getHosts();
-      Set<String> excludeList = hostsReader.getExcludedHosts();
-      return (hostsList.isEmpty() || hostsList.contains(hostName) || hostsList
-          .contains(ip))
-          && !(excludeList.contains(hostName) || excludeList.contains(ip));
-    }
+    Set<String> hostsList = new HashSet<String>();
+    Set<String> excludeList = new HashSet<String>();
+    hostsReader.getHostDetails(hostsList, excludeList);
+
+    return (hostsList.isEmpty() || hostsList.contains(hostName) || hostsList
+        .contains(ip))
+        && !(excludeList.contains(hostName) || excludeList.contains(ip));
   }
 
   @Override
@@ -466,17 +463,15 @@ public class NodesListManager extends CompositeService implements
   }
 
   public boolean isUntrackedNode(String hostName) {
-    boolean untracked;
     String ip = resolver.resolve(hostName);
 
-    synchronized (hostsReader) {
-      Set<String> hostsList = hostsReader.getHosts();
-      Set<String> excludeList = hostsReader.getExcludedHosts();
-      untracked = !hostsList.isEmpty() &&
-          !hostsList.contains(hostName) && !hostsList.contains(ip) &&
-          !excludeList.contains(hostName) && !excludeList.contains(ip);
-    }
-    return untracked;
+    Set<String> hostsList = new HashSet<String>();
+    Set<String> excludeList = new HashSet<String>();
+    hostsReader.getHostDetails(hostsList, excludeList);
+
+    return !hostsList.isEmpty() && !hostsList.contains(hostName)
+        && !hostsList.contains(ip) && !excludeList.contains(hostName)
+        && !excludeList.contains(ip);
   }
 
   /**