diff --git a/hadoop-hdfs-project/hadoop-hdfs/CHANGES.txt b/hadoop-hdfs-project/hadoop-hdfs/CHANGES.txt
index c1c01d517b6..259d010da39 100644
--- a/hadoop-hdfs-project/hadoop-hdfs/CHANGES.txt
+++ b/hadoop-hdfs-project/hadoop-hdfs/CHANGES.txt
@@ -688,6 +688,9 @@ Release 2.7.0 - UNRELEASED
     HDFS-5445. PacketReceiver populates the packetLen field in PacketHeader
     incorrectly (Jonathan Mace via Colin P. McCabe)
 
+    HDFS-7470. SecondaryNameNode need twice memory when calling
+    reloadFromImageFile. (zhaoyunjiong via cnauroth)
+
 Release 2.6.1 - UNRELEASED
 
   INCOMPATIBLE CHANGES
diff --git a/hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/server/blockmanagement/BlockManager.java b/hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/server/blockmanagement/BlockManager.java
index 03861070e33..f240569898f 100644
--- a/hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/server/blockmanagement/BlockManager.java
+++ b/hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/server/blockmanagement/BlockManager.java
@@ -3741,4 +3741,9 @@ public void shutdown() {
     stopReplicationInitializer();
     blocksMap.close();
   }
+  
+  public void clear() {
+    clearQueues();
+    blocksMap.clear();
+  }
 }
diff --git a/hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/server/blockmanagement/BlocksMap.java b/hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/server/blockmanagement/BlocksMap.java
index 6664034abe3..d532e748b6b 100644
--- a/hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/server/blockmanagement/BlocksMap.java
+++ b/hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/server/blockmanagement/BlocksMap.java
@@ -86,9 +86,13 @@ public Iterator<BlockInfo> iterator() {
 
 
   void close() {
+    clear();
+    blocks = null;
+  }
+  
+  void clear() {
     if (blocks != null) {
       blocks.clear();
-      blocks = null;
     }
   }
 
diff --git a/hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/server/namenode/FSNamesystem.java b/hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/server/namenode/FSNamesystem.java
index bcc0f5c1743..e7bf8e9a152 100644
--- a/hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/server/namenode/FSNamesystem.java
+++ b/hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/server/namenode/FSNamesystem.java
@@ -596,6 +596,7 @@ void clear() {
     snapshotManager.clearSnapshottableDirs();
     cacheManager.clear();
     setImageLoaded(false);
+    blockManager.clear();
   }
 
   @VisibleForTesting