将注册中心Erueka改为Zookeeper后，HystrixStreamTask报空指针异常

[dengly]

错误信息如下

2018-09-27 13:45:40.446 ERROR 39215 --- [ask-scheduler-5] o.s.c.n.h.stream.HystrixStreamTask       : Error adding metrics to queue

java.lang.NullPointerException: null
	at org.springframework.cloud.netflix.hystrix.stream.HystrixStreamTask.addServiceData(HystrixStreamTask.java:377)
	at org.springframework.cloud.netflix.hystrix.stream.HystrixStreamTask.gatherMetrics(HystrixStreamTask.java:134)
	at sun.reflect.GeneratedMethodAccessor190.invoke(Unknown Source)
	at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
	at java.lang.reflect.Method.invoke(Method.java:498)
	at org.springframework.scheduling.support.ScheduledMethodRunnable.run(ScheduledMethodRunnable.java:65)
	at org.springframework.scheduling.support.DelegatingErrorHandlingRunnable.run(DelegatingErrorHandlingRunnable.java:54)
	at java.util.concurrent.Executors$RunnableAdapter.call(Executors.java:511)
	at java.util.concurrent.FutureTask.runAndReset$$$capture(FutureTask.java:308)
	at java.util.concurrent.FutureTask.runAndReset(FutureTask.java)
	at java.util.concurrent.ScheduledThreadPoolExecutor$ScheduledFutureTask.access$301(ScheduledThreadPoolExecutor.java:180)
	at java.util.concurrent.ScheduledThreadPoolExecutor$ScheduledFutureTask.run(ScheduledThreadPoolExecutor.java:294)
	at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1142)
	at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:617)
	at java.lang.Thread.run(Thread.java:748)

经过调试发现在org.springframework.cloud.netflix.hystrix.stream.HystrixStreamTask中的addServiceData方法报错来的，原因是this.discoveryClient.getLocalServiceInstance()是null，而this.discoveryClient的类型是org.springframework.cloud.zookeeper.discovery.ZookeeperDiscoveryClient。ZookeeperDiscoveryClient的getLocalServiceInstance()（代码如下）返回是null。

public ServiceInstance getLocalServiceInstance() {
        if (this.zookeeperServiceDiscovery == null) {
            return null;
        } else {
            org.apache.curator.x.discovery.ServiceInstance<ZookeeperInstance> serviceInstance = (org.apache.curator.x.discovery.ServiceInstance)this.zookeeperServiceDiscovery.getServiceInstanceRef().get();
            return serviceInstance == null ? null : createServiceInstance(serviceInstance.getName(), serviceInstance);
        }
    }

调试发现走了else部分，(org.apache.curator.x.discovery.ServiceInstance)this.zookeeperServiceDiscovery.getServiceInstanceRef().get()返回值是null。目前还没找到解决方案。

[dengly]

解决方案，修改配置

spring.cloud.zookeeper.discovery.register=true