diff --git a/common/src/main/java/org/apache/rocketmq/common/utils/NetworkUtil.java b/common/src/main/java/org/apache/rocketmq/common/utils/NetworkUtil.java
index 6d454925f6b..c884563886a 100644
--- a/common/src/main/java/org/apache/rocketmq/common/utils/NetworkUtil.java
+++ b/common/src/main/java/org/apache/rocketmq/common/utils/NetworkUtil.java
@@ -193,6 +193,9 @@ public static String denormalizeHostAddress(final String bracketedAddress) {
 
     public static SocketAddress string2SocketAddress(final String addr) {
         int split = addr.lastIndexOf(":");
+        if (split < 0) {
+            throw new IllegalArgumentException("Invalid socket address, missing ':': " + addr);
+        }
         String host = addr.substring(0, split);
         String port = addr.substring(split + 1);
         return new InetSocketAddress(host, Integer.parseInt(port));
@@ -201,7 +204,9 @@ public static SocketAddress string2SocketAddress(final String addr) {
     public static String socketAddress2String(final SocketAddress addr) {
         StringBuilder sb = new StringBuilder();
         InetSocketAddress inetSocketAddress = (InetSocketAddress) addr;
-        sb.append(inetSocketAddress.getAddress().getHostAddress());
+        // getAddress() returns null when the hostname could not be resolved; fall back to the host string.
+        InetAddress address = inetSocketAddress.getAddress();
+        sb.append(address != null ? address.getHostAddress() : inetSocketAddress.getHostString());
         sb.append(":");
         sb.append(inetSocketAddress.getPort());
         return sb.toString();
diff --git a/store/src/main/java/org/apache/rocketmq/store/index/IndexService.java b/store/src/main/java/org/apache/rocketmq/store/index/IndexService.java
index 1a180e4442b..94a279550a9 100644
--- a/store/src/main/java/org/apache/rocketmq/store/index/IndexService.java
+++ b/store/src/main/java/org/apache/rocketmq/store/index/IndexService.java
@@ -92,11 +92,16 @@ public boolean load(final boolean lastExitOK) {
     }
 
     public long getTotalSize() {
-        if (indexFileList.isEmpty()) {
-            return 0;
-        }
+        this.readWriteLock.readLock().lock();
+        try {
+            if (indexFileList.isEmpty()) {
+                return 0;
+            }
 
-        return (long) indexFileList.get(0).getFileSize() * indexFileList.size();
+            return (long) indexFileList.get(0).getFileSize() * indexFileList.size();
+        } finally {
+            this.readWriteLock.readLock().unlock();
+        }
     }
 
     public void deleteExpiredFile(long offset) {