[Dubbo-4323]fix use AtomicInteger instead of volatile to inc (apache#4324)

Signed-off-by: slievrly <[email protected]>

Author: slievrly

dubbo-filter/dubbo-filter-cache/src/main/java/org/apache/dubbo/cache/support/expiring/ExpiringMap.java

@@ -22,6 +22,7 @@
 import java.util.Map;
 import java.util.Set;
 import java.util.concurrent.ConcurrentHashMap;
+import java.util.concurrent.atomic.AtomicInteger;
 import java.util.concurrent.atomic.AtomicLong;
 
 /**
@@ -40,7 +41,7 @@ public class ExpiringMap<K, V> implements Map<K, V> {
      */
     private static final int DEFAULT_EXPIRATION_INTERVAL = 1;
 
-    private static volatile int expireCount = 1;
+    private static AtomicInteger expireCount = new AtomicInteger(1);
 
     private final ConcurrentHashMap<K, ExpiryObject> delegateMap;
 
@@ -263,7 +264,7 @@ public String toString() {
         }
 
         public ExpireThread() {
-            expirerThread = new Thread(this, "ExpiryMapExpire-" + expireCount++);
+            expirerThread = new Thread(this, "ExpiryMapExpire-" + expireCount.getAndIncrement());
             expirerThread.setDaemon(true);
         }