close zkclientx if necessary when stop canal

deployer/src/main/java/com/alibaba/otter/canal/deployer/CanalController.java

@@ -454,6 +454,10 @@ public class CanalController {
         // 释放canal的工作节点
         releaseCid(ZookeeperPathUtils.getCanalClusterNode(ip + ":" + port));
         logger.info("## stop the canal server[{}:{}]", ip, port);
+        
+        if (zkclientx != null) {
+            zkclientx.close();
+        }
     }
 
     private void initCid(String path) {