diff --git a/hadoop-yarn-project/CHANGES.txt b/hadoop-yarn-project/CHANGES.txt
index 3f04aa03ea8..bd0c29195c2 100644
--- a/hadoop-yarn-project/CHANGES.txt
+++ b/hadoop-yarn-project/CHANGES.txt
@@ -52,7 +52,10 @@ Release 2.7.2 - UNRELEASED
     YARN-4047. ClientRMService getApplications has high scheduler lock contention
     (Jason Lowe via jianhe)
 
-Release 2.7.1 - 2015-07-06 
+    YARN-3857: Memory leak in ResourceManager with SIMPLE mode.
+    (mujunchao via zxu)
+
+Release 2.7.1 - 2015-07-06
 
   INCOMPATIBLE CHANGES
 
diff --git a/hadoop-yarn-project/hadoop-yarn/hadoop-yarn-server/hadoop-yarn-server-resourcemanager/src/main/java/org/apache/hadoop/yarn/server/resourcemanager/rmapp/attempt/RMAppAttemptImpl.java b/hadoop-yarn-project/hadoop-yarn/hadoop-yarn-server/hadoop-yarn-server-resourcemanager/src/main/java/org/apache/hadoop/yarn/server/resourcemanager/rmapp/attempt/RMAppAttemptImpl.java
index 9ed5c32c7e8..230bbeb736b 100644
--- a/hadoop-yarn-project/hadoop-yarn/hadoop-yarn-server/hadoop-yarn-server-resourcemanager/src/main/java/org/apache/hadoop/yarn/server/resourcemanager/rmapp/attempt/RMAppAttemptImpl.java
+++ b/hadoop-yarn-project/hadoop-yarn/hadoop-yarn-server/hadoop-yarn-server-resourcemanager/src/main/java/org/apache/hadoop/yarn/server/resourcemanager/rmapp/attempt/RMAppAttemptImpl.java
@@ -1308,9 +1308,11 @@ public class RMAppAttemptImpl implements RMAppAttempt, Recoverable {
 
       // register the ClientTokenMasterKey after it is saved in the store,
       // otherwise client may hold an invalid ClientToken after RM restarts.
-      appAttempt.rmContext.getClientToAMTokenSecretManager()
-      .registerApplication(appAttempt.getAppAttemptId(),
-        appAttempt.getClientTokenMasterKey());
+      if (UserGroupInformation.isSecurityEnabled()) {
+        appAttempt.rmContext.getClientToAMTokenSecretManager()
+            .registerApplication(appAttempt.getAppAttemptId(),
+            appAttempt.getClientTokenMasterKey());
+      }
     }
   }
 
diff --git a/hadoop-yarn-project/hadoop-yarn/hadoop-yarn-server/hadoop-yarn-server-resourcemanager/src/main/java/org/apache/hadoop/yarn/server/resourcemanager/security/ClientToAMTokenSecretManagerInRM.java b/hadoop-yarn-project/hadoop-yarn/hadoop-yarn-server/hadoop-yarn-server-resourcemanager/src/main/java/org/apache/hadoop/yarn/server/resourcemanager/security/ClientToAMTokenSecretManagerInRM.java
index 4fbe2cea517..4047bd5731a 100644
--- a/hadoop-yarn-project/hadoop-yarn/hadoop-yarn-server/hadoop-yarn-server-resourcemanager/src/main/java/org/apache/hadoop/yarn/server/resourcemanager/security/ClientToAMTokenSecretManagerInRM.java
+++ b/hadoop-yarn-project/hadoop-yarn/hadoop-yarn-server/hadoop-yarn-server-resourcemanager/src/main/java/org/apache/hadoop/yarn/server/resourcemanager/security/ClientToAMTokenSecretManagerInRM.java
@@ -22,6 +22,7 @@ import java.util.HashMap;
 import java.util.Map;
 
 import javax.crypto.SecretKey;
+import com.google.common.annotations.VisibleForTesting;
 
 import org.apache.hadoop.yarn.api.records.ApplicationAttemptId;
 import org.apache.hadoop.yarn.security.client.BaseClientToAMTokenSecretManager;
@@ -61,4 +62,10 @@ public class ClientToAMTokenSecretManagerInRM extends
       ApplicationAttemptId applicationAttemptID) {
     return this.masterKeys.get(applicationAttemptID);
   }
+
+  @VisibleForTesting
+  public synchronized boolean hasMasterKey(
+      ApplicationAttemptId applicationAttemptID) {
+    return this.masterKeys.containsKey(applicationAttemptID);
+  }
 }
diff --git a/hadoop-yarn-project/hadoop-yarn/hadoop-yarn-server/hadoop-yarn-server-resourcemanager/src/test/java/org/apache/hadoop/yarn/server/resourcemanager/rmapp/attempt/TestRMAppAttemptTransitions.java b/hadoop-yarn-project/hadoop-yarn/hadoop-yarn-server/hadoop-yarn-server-resourcemanager/src/test/java/org/apache/hadoop/yarn/server/resourcemanager/rmapp/attempt/TestRMAppAttemptTransitions.java
index 9afb5a908de..c8b6bd07b88 100644
--- a/hadoop-yarn-project/hadoop-yarn/hadoop-yarn-server/hadoop-yarn-server-resourcemanager/src/test/java/org/apache/hadoop/yarn/server/resourcemanager/rmapp/attempt/TestRMAppAttemptTransitions.java
+++ b/hadoop-yarn-project/hadoop-yarn/hadoop-yarn-server/hadoop-yarn-server-resourcemanager/src/test/java/org/apache/hadoop/yarn/server/resourcemanager/rmapp/attempt/TestRMAppAttemptTransitions.java
@@ -1393,6 +1393,38 @@ public class TestRMAppAttemptTransitions {
     Assert.assertNull(token);
   }
 
+  // this is to test master key is saved in the secret manager only after
+  // attempt is launched and in secure-mode
+  @Test
+  public void testApplicationAttemptMasterKey() throws Exception {
+    Container amContainer = allocateApplicationAttempt();
+    ApplicationAttemptId appid = applicationAttempt.getAppAttemptId();
+    boolean isMasterKeyExisted = false;
+
+    // before attempt is launched, can not get MasterKey
+    isMasterKeyExisted = clientToAMTokenManager.hasMasterKey(appid);
+    Assert.assertFalse(isMasterKeyExisted);
+
+    launchApplicationAttempt(amContainer);
+    // after attempt is launched and in secure mode, can get MasterKey
+    isMasterKeyExisted = clientToAMTokenManager.hasMasterKey(appid);
+    if (isSecurityEnabled) {
+      Assert.assertTrue(isMasterKeyExisted);
+      Assert.assertNotNull(clientToAMTokenManager.getMasterKey(appid));
+    } else {
+      Assert.assertFalse(isMasterKeyExisted);
+    }
+
+    applicationAttempt.handle(new RMAppAttemptEvent(applicationAttempt
+      .getAppAttemptId(), RMAppAttemptEventType.KILL));
+    assertEquals(YarnApplicationAttemptState.LAUNCHED,
+        applicationAttempt.createApplicationAttemptState());
+    sendAttemptUpdateSavedEvent(applicationAttempt);
+    // after attempt is killed, can not get MasterKey
+    isMasterKeyExisted = clientToAMTokenManager.hasMasterKey(appid);
+    Assert.assertFalse(isMasterKeyExisted);
+  }
+
   @Test
   public void testFailedToFailed() {
     // create a failed attempt.