Fix ServerStatusService.statusWatchers concurrent modification. (#12884)

Author: weixiang1862

docs/en/changes/changes.md

@@ -36,6 +36,7 @@
 * BanyanDB: Speed up OAP booting while initializing BanyanDB.
 * BanyanDB: Support `@EnableSort` on the column to enable sorting for `IndexRule` and set the default to false.
 * Support `Get Effective TTL Configurations` API.
+* Fix `ServerStatusService.statusWatchers` concurrent modification.
 
 #### UI
 

oap-server/server-core/src/main/java/org/apache/skywalking/oap/server/core/status/ServerStatusService.java

@@ -18,8 +18,8 @@
 
 package org.apache.skywalking.oap.server.core.status;
 
-import java.util.ArrayList;
 import java.util.List;
+import java.util.concurrent.CopyOnWriteArrayList;
 import lombok.Getter;
 import lombok.RequiredArgsConstructor;
 import org.apache.skywalking.oap.server.core.CoreModuleConfig;
@@ -46,7 +46,7 @@ public class ServerStatusService implements Service {
     @Getter
     private ClusterStatus clusterStatus = new ClusterStatus();
 
-    private List<ServerStatusWatcher> statusWatchers = new ArrayList<>();
+    private List<ServerStatusWatcher> statusWatchers = new CopyOnWriteArrayList<>();
 
     private List<ApplicationConfiguration.ModuleConfiguration> configurations;