From 9275eeaa7a7b4a8b24955728338a928ad902686d Mon Sep 17 00:00:00 2001
From: caoyixiong <32847163+IanCao@users.noreply.github.com>
Date: Fri, 31 Aug 2018 18:09:07 +0800
Subject: [PATCH]  FIx NPE in InstanceMetricAlarmAssertWorker (#1614)

* add user

* add user

* FIx NPE in InstanceMetricAlarmAssertWorker
---
 .../worker/instance/InstanceMetricAlarmAssertWorker.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/InstanceMetricAlarmAssertWorker.java b/apm-collector/apm-collector-analysis/analysis-alarm/alarm-provider/src/main/java/org/apache/skywalking/apm/collector/analysis/alarm/provider/worker/instance/InstanceMetricAlarmAssertWorker.java
index a0e9ad1c2..c6cd39932 100644
--- a/apm-collector/apm-collector-analysis/analysis-alarm/alarm-provider/src/main/java/org/apache/skywalking/apm/collector/analysis/alarm/provider/worker/instance/InstanceMetricAlarmAssertWorker.java
+++ b/apm-collector/apm-collector-analysis/analysis-alarm/alarm-provider/src/main/java/org/apache/skywalking/apm/collector/analysis/alarm/provider/worker/instance/InstanceMetricAlarmAssertWorker.java
@@ -66,7 +66,7 @@ public class InstanceMetricAlarmAssertWorker extends AlarmAssertWorker<InstanceM
         Instance instance = instanceDAO.getInstance(alarm.getInstanceId());
         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();
         }