diff --git a/hadoop-yarn-project/CHANGES.txt b/hadoop-yarn-project/CHANGES.txt
index 3f55118889a..c7e65f12e1c 100644
--- a/hadoop-yarn-project/CHANGES.txt
+++ b/hadoop-yarn-project/CHANGES.txt
@@ -169,6 +169,9 @@ Release 2.7.0 - UNRELEASED
     YARN-2880. Added a test to make sure node labels will be recovered
     if RM restart is enabled. (Rohith Sharmaks via jianhe)
 
+    YARN-2996. Improved synchronization and I/O operations of FS- and Mem-
+    RMStateStore. (Yi Liu via zjshen)
+
   OPTIMIZATIONS
 
   BUG FIXES
diff --git a/hadoop-yarn-project/hadoop-yarn/hadoop-yarn-server/hadoop-yarn-server-resourcemanager/src/main/java/org/apache/hadoop/yarn/server/resourcemanager/recovery/FileSystemRMStateStore.java b/hadoop-yarn-project/hadoop-yarn/hadoop-yarn-server/hadoop-yarn-server-resourcemanager/src/main/java/org/apache/hadoop/yarn/server/resourcemanager/recovery/FileSystemRMStateStore.java
index 77836620b29..6e830a028ab 100644
--- a/hadoop-yarn-project/hadoop-yarn/hadoop-yarn-server/hadoop-yarn-server-resourcemanager/src/main/java/org/apache/hadoop/yarn/server/resourcemanager/recovery/FileSystemRMStateStore.java
+++ b/hadoop-yarn-project/hadoop-yarn/hadoop-yarn-server/hadoop-yarn-server-resourcemanager/src/main/java/org/apache/hadoop/yarn/server/resourcemanager/recovery/FileSystemRMStateStore.java
@@ -139,8 +139,8 @@ protected Version getCurrentVersion() {
   @Override
   protected synchronized Version loadVersion() throws Exception {
     Path versionNodePath = getNodePath(rootDirPath, VERSION_NODE);
-    if (fs.exists(versionNodePath)) {
-      FileStatus status = fs.getFileStatus(versionNodePath);
+    FileStatus status = getFileStatus(versionNodePath);
+    if (status != null) {
       byte[] data = readFile(versionNodePath, status.getLen());
       Version version =
           new VersionPBImpl(VersionProto.parseFrom(data));
@@ -165,9 +165,9 @@ protected synchronized void storeVersion() throws Exception {
   public synchronized long getAndIncrementEpoch() throws Exception {
     Path epochNodePath = getNodePath(rootDirPath, EPOCH_NODE);
     long currentEpoch = 0;
-    if (fs.exists(epochNodePath)) {
+    FileStatus status = getFileStatus(epochNodePath);
+    if (status != null) {
       // load current epoch
-      FileStatus status = fs.getFileStatus(epochNodePath);
       byte[] data = readFile(epochNodePath, status.getLen());
       Epoch epoch = new EpochPBImpl(EpochProto.parseFrom(data));
       currentEpoch = epoch.getEpoch();
@@ -201,13 +201,11 @@ private void loadAMRMTokenSecretManagerState(RMState rmState)
     checkAndResumeUpdateOperation(amrmTokenSecretManagerRoot);
     Path amrmTokenSecretManagerStateDataDir =
         new Path(amrmTokenSecretManagerRoot, AMRMTOKEN_SECRET_MANAGER_NODE);
-    FileStatus status;
-    try {
-      status = fs.getFileStatus(amrmTokenSecretManagerStateDataDir);
-      assert status.isFile();
-    } catch (FileNotFoundException ex) {
+    FileStatus status = getFileStatus(amrmTokenSecretManagerStateDataDir);
+    if (status == null) {
       return;
     }
+    assert status.isFile();
     byte[] data = readFile(amrmTokenSecretManagerStateDataDir, status.getLen());
     AMRMTokenSecretManagerStatePBImpl stateData =
         new AMRMTokenSecretManagerStatePBImpl(
@@ -466,7 +464,7 @@ public synchronized void removeRMDelegationTokenState(
   }
 
   @Override
-  protected void updateRMDelegationTokenState(
+  protected synchronized void updateRMDelegationTokenState(
       RMDelegationTokenIdentifier rmDTIdentifier, Long renewDate)
       throws Exception {
     storeOrUpdateRMDelegationTokenState(rmDTIdentifier, renewDate, true);
@@ -560,6 +558,14 @@ private byte[] readFile(Path inputPath, long len) throws Exception {
     }
   }
 
+  private FileStatus getFileStatus(Path path) throws Exception {
+    try {
+      return fs.getFileStatus(path);
+    } catch (FileNotFoundException e) {
+      return null;
+    }
+  }
+
   /*
    * In order to make this write atomic as a part of write we will first write
    * data to .tmp file and then rename it. Here we are assuming that rename is
diff --git a/hadoop-yarn-project/hadoop-yarn/hadoop-yarn-server/hadoop-yarn-server-resourcemanager/src/main/java/org/apache/hadoop/yarn/server/resourcemanager/recovery/MemoryRMStateStore.java b/hadoop-yarn-project/hadoop-yarn/hadoop-yarn-server/hadoop-yarn-server-resourcemanager/src/main/java/org/apache/hadoop/yarn/server/resourcemanager/recovery/MemoryRMStateStore.java
index 3646949b604..8cd776e6044 100644
--- a/hadoop-yarn-project/hadoop-yarn/hadoop-yarn-server/hadoop-yarn-server-resourcemanager/src/main/java/org/apache/hadoop/yarn/server/resourcemanager/recovery/MemoryRMStateStore.java
+++ b/hadoop-yarn-project/hadoop-yarn/hadoop-yarn-server/hadoop-yarn-server-resourcemanager/src/main/java/org/apache/hadoop/yarn/server/resourcemanager/recovery/MemoryRMStateStore.java
@@ -91,15 +91,16 @@ protected synchronized void closeInternal() throws Exception {
   }
 
   @Override
-  public void storeApplicationStateInternal(
+  public synchronized void storeApplicationStateInternal(
       ApplicationId appId, ApplicationStateData appState)
       throws Exception {
     state.appState.put(appId, appState);
   }
 
   @Override
-  public void updateApplicationStateInternal(ApplicationId appId,
-      ApplicationStateData appState) throws Exception {
+  public synchronized void updateApplicationStateInternal(
+      ApplicationId appId, ApplicationStateData appState) 
+      throws Exception {
     LOG.info("Updating final state " + appState.getState() + " for app: "
         + appId);
     if (state.appState.get(appId) != null) {
@@ -186,7 +187,7 @@ public synchronized void removeRMDelegationTokenState(
   }
 
   @Override
-  protected void updateRMDelegationTokenState(
+  protected synchronized void updateRMDelegationTokenState(
       RMDelegationTokenIdentifier rmDTIdentifier, Long renewDate)
       throws Exception {
     removeRMDelegationTokenState(rmDTIdentifier);
@@ -237,7 +238,7 @@ protected Version getCurrentVersion() {
   }
 
   @Override
-  public void storeOrUpdateAMRMTokenSecretManagerState(
+  public synchronized void storeOrUpdateAMRMTokenSecretManagerState(
       AMRMTokenSecretManagerState amrmTokenSecretManagerState,
       boolean isUpdate) {
     if (amrmTokenSecretManagerState != null) {