[DS-6737][MasterServer] fix event handle twice (#6738)

Co-authored-by: caishunfeng <534328519@qq.com>

dolphinscheduler-server/src/main/java/org/apache/dolphinscheduler/server/master/runner/WorkflowExecuteThread.java

@@ -105,10 +105,7 @@ public class WorkflowExecuteThread implements Runnable {
      * runing TaskNode
      */
     private final Map<Integer, ITaskProcessor> activeTaskProcessorMaps = new ConcurrentHashMap<>();
-    /**
+
-     * task exec service
-     */
-    private final ExecutorService taskExecService;
     /**
      * process instance
      */
@@ -217,9 +214,6 @@ public class WorkflowExecuteThread implements Runnable {
 
         this.processInstance = processInstance;
         this.masterConfig = masterConfig;
-        int masterTaskExecNum = masterConfig.getMasterExecTaskNum();
-        this.taskExecService = ThreadUtils.newDaemonFixedThreadExecutor("Master-Task-Exec-Thread",
-                masterTaskExecNum);
         this.nettyExecutorManager = nettyExecutorManager;
         this.processAlertManager = processAlertManager;
         this.taskTimeoutCheckList = taskTimeoutCheckList;
@@ -228,8 +222,11 @@ public class WorkflowExecuteThread implements Runnable {
     @Override
     public void run() {
         try {
+            if (!this.isStart()) {
                 startProcess();
+            } else {
                 handleEvents();
+            }
         } catch (Exception e) {
             logger.error("handler error:", e);
         }