From a29a8d7c09641b7c4e722d03c9816d15d68855c4 Mon Sep 17 00:00:00 2001
From: caoyixiong <32847163+IanCao@users.noreply.github.com>
Date: Sun, 19 Aug 2018 10:50:06 +0800
Subject: [PATCH] Fix NPE in alarm content generation. (#1558)
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* Update InstanceReferenceMetricAlarmAssertWorker.java

增加osInfo 判空

* Update InstanceReferenceMetricAlarmAssertWorker.java

增加osinfo 判空
---
 .../instance/InstanceReferenceMetricAlarmAssertWorker.java      | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/apm-collector/apm-collector-analysis/analysis-alarm/alarm-provider/src/main/java/org/apache/skywalking/apm/collector/analysis/alarm/provider/worker/instance/InstanceReferenceMetricAlarmAssertWorker.java b/apm-collector/apm-collector-analysis/analysis-alarm/alarm-provider/src/main/java/org/apache/skywalking/apm/collector/analysis/alarm/provider/worker/instance/InstanceReferenceMetricAlarmAssertWorker.java
index 997c93ee8..9f5ffc389 100644
--- a/apm-collector/apm-collector-analysis/analysis-alarm/alarm-provider/src/main/java/org/apache/skywalking/apm/collector/analysis/alarm/provider/worker/instance/InstanceReferenceMetricAlarmAssertWorker.java
+++ b/apm-collector/apm-collector-analysis/analysis-alarm/alarm-provider/src/main/java/org/apache/skywalking/apm/collector/analysis/alarm/provider/worker/instance/InstanceReferenceMetricAlarmAssertWorker.java
@@ -68,7 +68,7 @@ public class InstanceReferenceMetricAlarmAssertWorker extends AlarmAssertWorker<
         Instance instance = instanceDAO.getInstance(alarm.getBehindInstanceId());
         JsonObject osInfo = gson.fromJson(instance.getOsInfo(), JsonObject.class);
         String serverName = Const.UNKNOWN;
-        if (osInfo.has("hostName")) {
+        if (osInfo != null && osInfo.has("hostName")) {
             serverName = osInfo.get("hostName").getAsString();
         }