From b905f7bd5a58e684004badba483808ded015275e Mon Sep 17 00:00:00 2001
From: KomachiSion <263976490@qq.com>
Date: Tue, 15 Sep 2020 13:21:28 +0800
Subject: [PATCH] Fix NullPointerException when no subscriber for slow event

---
 .../alibaba/nacos/common/notify/DefaultSharePublisher.java    | 4 ++++
 .../com/alibaba/nacos/common/notify/NotifyCenterTest.java     | 1 +
 2 files changed, 5 insertions(+)

diff --git a/common/src/main/java/com/alibaba/nacos/common/notify/DefaultSharePublisher.java b/common/src/main/java/com/alibaba/nacos/common/notify/DefaultSharePublisher.java
index 3028423f7f7..a2fa996d1db 100644
--- a/common/src/main/java/com/alibaba/nacos/common/notify/DefaultSharePublisher.java
+++ b/common/src/main/java/com/alibaba/nacos/common/notify/DefaultSharePublisher.java
@@ -96,6 +96,10 @@ public void receiveEvent(Event event) {
         
         // Get for Map, the algorithm is O(1).
         Set<Subscriber> subscribers = subMappings.get(slowEventType);
+        if (null == subscribers) {
+            LOGGER.debug("[NotifyCenter] No subscribers for slow event {}", slowEventType.getName());
+            return;
+        }
         
         // Notification single event subscriber
         for (Subscriber subscriber : subscribers) {
diff --git a/common/src/test/java/com/alibaba/nacos/common/notify/NotifyCenterTest.java b/common/src/test/java/com/alibaba/nacos/common/notify/NotifyCenterTest.java
index a7163938d00..d1abd7c1e73 100644
--- a/common/src/test/java/com/alibaba/nacos/common/notify/NotifyCenterTest.java
+++ b/common/src/test/java/com/alibaba/nacos/common/notify/NotifyCenterTest.java
@@ -132,6 +132,7 @@ public Class<? extends Event> subscribeType() {
                 return ExpireEvent.class;
             }
             
+            @Override
             public boolean ignoreExpireEvent() {
                 return true;
             }