diff --git a/src/main/java/com/actiontech/dble/net/handler/BackEndRecycleRunnable.java b/src/main/java/com/actiontech/dble/net/handler/BackEndRecycleRunnable.java
index 682162106..bd986e65d 100644
--- a/src/main/java/com/actiontech/dble/net/handler/BackEndRecycleRunnable.java
+++ b/src/main/java/com/actiontech/dble/net/handler/BackEndRecycleRunnable.java
@@ -29,11 +29,15 @@ public class BackEndRecycleRunnable implements Runnable, BackEndCleaner {
 
     @Override
     public void run() {
+        BackendConnection conn = service.getConnection();
+        if (conn.isClosed()) {
+            return;
+        }
+
         try {
             lock.lock();
             try {
                 if (service.isRowDataFlowing()) {
-                    BackendConnection conn = service.getConnection();
                     if (!condRelease.await(10, TimeUnit.MILLISECONDS)) {
                         if (!conn.isClosed()) {
                             conn.businessClose("recycle time out");
@@ -56,11 +60,12 @@ public class BackEndRecycleRunnable implements Runnable, BackEndCleaner {
 
 
     public void signal() {
-        lock.lock();
-        try {
-            condRelease.signal();
-        } finally {
-            lock.unlock();
+        if (lock.tryLock()) {
+            try {
+                condRelease.signal();
+            } finally {
+                lock.unlock();
+            }
         }
     }
 
diff --git a/src/main/java/com/actiontech/dble/services/mysqlsharding/MySQLResponseService.java b/src/main/java/com/actiontech/dble/services/mysqlsharding/MySQLResponseService.java
index 4047da13e..3ae6c2720 100644
--- a/src/main/java/com/actiontech/dble/services/mysqlsharding/MySQLResponseService.java
+++ b/src/main/java/com/actiontech/dble/services/mysqlsharding/MySQLResponseService.java
@@ -699,6 +699,10 @@ public class MySQLResponseService extends VariablesService {
     }
 
     public void signal() {
+        if (connection.isClosed()) {
+            return;
+        }
+
         if (recycler != null) {
             recycler.signal();
         }