src/java.naming/share/classes/com/sun/jndi/ldap/EventSupport.java

@@ -1,7 +1,7 @@
 /*
- * Copyright (c) 1999, 2019, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 1999, 2020, Oracle and/or its affiliates. All rights reserved.
  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
  *
  * This code is free software; you can redistribute it and/or modify it
  * under the terms of the GNU General Public License version 2 only, as
  * published by the Free Software Foundation.  Oracle designates this

@@ -248,12 +248,17 @@
       */
     synchronized void removeDeadNotifier(NotifierArgs info) {
         if (debug) {
             System.err.println("EventSupport.removeDeadNotifier: " + info.name);
         }
+        if (notifiers != null) {
+            // Only do this if cleanup() not been triggered, otherwise here
+            // will throw NullPointerException since notifiers will be set to
+            // null in cleanup()
         notifiers.remove(info);
     }
+    }
 
     /**
      * Fire an event to unsolicited listeners.
      * package private;
      * Called by LdapCtx when its clnt receives an unsolicited notification.

@@ -327,10 +332,15 @@
      * them to the registered listeners.
      * Package private; used by NamingEventNotifier to fire events
      */
     synchronized void queueEvent(EventObject event,
                                  Vector<? extends NamingListener> vector) {
+        if (notifiers == null) {
+            // That means cleanup() already done, not queue event anymore,
+            // otherwise, new created EventQueue will not been cleanup.
+            return;
+        }
         if (eventQueue == null)
             eventQueue = new EventQueue();
 
         /*
          * Copy the vector in order to freeze the state of the set