diff --git a/scheduler/src/main/java/com/zfoo/scheduler/util/LazyCache.java b/scheduler/src/main/java/com/zfoo/scheduler/util/LazyCache.java
index 5cab2f3b..f2e3083f 100644
--- a/scheduler/src/main/java/com/zfoo/scheduler/util/LazyCache.java
+++ b/scheduler/src/main/java/com/zfoo/scheduler/util/LazyCache.java
@@ -155,7 +155,7 @@ public class LazyCache<K, V> {
         removeListener.accept(removeList, removalCause);
     }
 
-    private void checkMaximumSize() {
+    private synchronized void checkMaximumSize() {
         if (cacheMap.size() > backPressureSize) {
             var removeList = cacheMap.values()
                     .stream()