diff --git a/upms/upms-biz/src/main/java/com/rax/vital/timer/VitalSignTimerWS.java b/upms/upms-biz/src/main/java/com/rax/vital/timer/VitalSignTimerWS.java
index 70b9688..5d14391 100644
--- a/upms/upms-biz/src/main/java/com/rax/vital/timer/VitalSignTimerWS.java
+++ b/upms/upms-biz/src/main/java/com/rax/vital/timer/VitalSignTimerWS.java
@@ -84,7 +84,7 @@ public class VitalSignTimerWS {
 
 	public void createAndSendWSMessageMongo(String database, String username, WebSocketSession session) {
 
-		synchronized (username) {
+		synchronized (this) {
 			if (!masterControlMap.containsKey(database)) {
 				masterControlMap.put(database, username);
 			}
@@ -139,7 +139,7 @@ public class VitalSignTimerWS {
 	}
 
 	public void createAndSendMessageMySQL(String database, String username, WebSocketSession session) {
-		synchronized (username) {
+		synchronized (this) {
 			if (!masterControlMap.containsKey(database)) {
 				masterControlMap.put(database, username);
 			}
@@ -223,7 +223,7 @@ public class VitalSignTimerWS {
 	}
 
 	public void changeWSAIFlag(String database, String username, WebSocketSession session, String flag, String medicine, String value) throws IOException {
-		synchronized (username) {
+		synchronized (this) {
 			JSONObject result = new JSONObject();
 			if (masterControlMap.containsKey(database) && masterControlMap.get(database).equals(username)) {
 				if (!userDatabaseSessionMap.containsKey(database)) {