目录

1. Hystrix监控Ribbon
2. 监控端点与数据
3. 测试步骤
4. 监控对于Feign
5. 代码示例：
6. Hystrix Dashboard

Hystrix监控Ribbon

除了隔离依赖服务的调用以外，Hystrix还提供了近实时的监控，Hystrix会实时、累加地记录所有关于HystrixCommand的执行信息，包括每秒执行多少请求多少成功，多少失败等。Netflix通过hystrix-metrics-event-stream项目实现了对以上指标的监控。

上文提到的microservice-consumer-ribbon-with-hystrix项目已经具备对Hystrix监控的能力，下面我们进入测试。

Hystrix提供了监控Hystrix Command的能力，本节来详细探讨。

监控端点与数据

应用整合Hystrix，同时应用包含spring-boot-starter-actuator 依赖，就会存在一个/actuator/hystrix.stream 端点，用来监控Hystrix Command。当被@HystrixCommand 注解了的方法被调用时，就会产生监控信息，并暴露到该端点中。当然，该端点默认是不会暴露的，需使用如下配置将其暴露。

management:
  endpoints:
    web:
      exposure:
        include: 'hystrix.stream'
        include: '*'

此时，访问/actuator/hystrix.stream 可返回如下结果：

{"type":"HystrixCommand","name":"findById","group":"MovieController","currentTime":1547905939151,"isCircuitBreakerOpen":false,"errorPercentage":0,"errorCount":0,"requestCount":0,"rollingCountBadRequests":0,"rollingCountCollapsedRequests":0,"rollingCountEmit":0,"rollingCountExceptionsThrown":0,"rollingCountFailure":0,"rollingCountFallbackEmit":0,"rollingCountFallbackFailure":0,"rollingCountFallbackMissing":0,"rollingCountFallbackRejection":0,"rollingCountFallbackSuccess":0,"rollingCountResponsesFromCache":0,"rollingCountSemaphoreRejected":0,"rollingCountShortCircuited":0,"rollingCountSuccess":0,"rollingCountThreadPoolRejected":0,"rollingCountTimeout":0,"currentConcurrentExecutionCount":0,"rollingMaxConcurrentExecutionCount":0,"latencyExecute_mean":0,"latencyExecute":{"0":0,"25":0,"50":0,"75":0,"90":0,"95":0,"99":0,"99.5":0,"100":0},"latencyTotal_mean":0,"latencyTotal":{"0":0,"25":0,"50":0,"75":0,"90":0,"95":0,"99":0,"99.5":0,"100":0},"propertyValue_circuitBreakerRequestVolumeThreshold":20,"propertyValue_circuitBreakerSleepWindowInMilliseconds":5000,"propertyValue_circuitBreakerErrorThresholdPercentage":50,"propertyValue_circuitBreakerForceOpen":false,"propertyValue_circuitBreakerForceClosed":false,"propertyValue_circuitBreakerEnabled":true,"propertyValue_executionIsolationStrategy":"THREAD","propertyValue_executionIsolationThreadTimeoutInMilliseconds":1000,"propertyValue_executionTimeoutInMilliseconds":1000,"propertyValue_executionIsolationThreadInterruptOnTimeout":true,"propertyValue_executionIsolationThreadPoolKeyOverride":null,"propertyValue_executionIsolationSemaphoreMaxConcurrentRequests":10,"propertyValue_fallbackIsolationSemaphoreMaxConcurrentRequests":10,"propertyValue_metricsRollingStatisticalWindowInMilliseconds":10000,"propertyValue_requestCacheEnabled":true,"propertyValue_requestLogEnabled":true,"reportingHosts":1,"threadPool":"MovieController"}

测试步骤

1. 启动：microservice-discovery-eureka
2. 启动：microservice-provider
3. 启动：microservice-consumer-ribbon-with-hystrix
4. 访问：http://localhost:8010/ribbon/user/1 ，注意：该步骤不能省略，因为如果应用的所有接口都未被调用，将只会看到一个ping

5. 访问：http://localhost:8010/actuator/hystrix.stream，可以看到类似如下输出：

data: {"type":"HystrixCommand","name":"findById","group":"RibbonHystrixService","currentTime":1472658867784,"isCircuitBreakerOpen":false,"errorPercentage":0,"errorCount":0,"requestCount":0,"rollingCountBadRequests":0....}

并且会不断刷新以获取实时的监控数据。但是纯文字的输出可读性实在是太差，运维人员很难一眼看出系统当前的运行状态。那么是不是有可视化的工具呢？

监控对于Feign

前面讲过Feign默认已经整合了Hystrix，但这个整合其实是“不完整”，因为它默认不带有监控端点，如果你在使用Feign的同时，也想使用监控端点，需按照如下步骤操作：

• 加依赖

<dependency>
  <groupId>org.springframework.cloud</groupId>
  <artifactId>spring-cloud-starter-netflix-hystrix</artifactId>
</dependency>

• 在启动类上添加注解@EnableCircuitBreaker
• 在application.yml 中添加如下配置：

management:
  endpoints:
    web:
      exposure:
        include: 'hystrix.stream'

测试：http://127.0.0.1:8020/actuator/hystrix.stream

代码示例：

microservice-consumer-movie-feign-hystrix-stream

Hystrix Dashboard

Hystrix Dashboard可以可视化查看实时监控数据。我们可以下载hystrix-dashboard的war包部署到诸如Tomcat之类的容器中，本文不做赘述。另外Spring Cloud也提供了Hystrix Dashboard的整合，下面我们看看Spring Cloud是怎么玩转Hystrix Dashboard的。

新建一个maven项目，在pom.xml中添加如下内容：

<?xml version="1.0" encoding="UTF-8"?>
<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
         xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
    <modelVersion>4.0.0</modelVersion>
    <parent>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-parent</artifactId>
        <version>2.1.4.RELEASE</version>
        <relativePath/> <!-- lookup parent from repository -->
    </parent>
    <groupId>com.example</groupId>
    <artifactId>microservice-hystrix-dashboard</artifactId>
    <version>0.0.1-SNAPSHOT</version>
    <name>microservice-hystrix-dashboard</name>
    <description>Demo project for Spring Boot</description>

    <properties>
        <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
        <java.version>1.8</java.version>
    </properties>

    <dependencies>
        <dependency>
            <groupId>org.springframework.cloud</groupId>
            <artifactId>spring-cloud-starter-netflix-hystrix-dashboard</artifactId>
        </dependency>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-test</artifactId>
            <scope>test</scope>
        </dependency>
    </dependencies>

    <!-- 引入spring cloud的依赖 -->
    <dependencyManagement>
        <dependencies>
            <dependency>
                <groupId>org.springframework.cloud</groupId>
                <artifactId>spring-cloud-dependencies</artifactId>
                <version>Greenwich.SR1</version>
                <type>pom</type>
                <scope>import</scope>
            </dependency>
        </dependencies>
    </dependencyManagement>

    <build>
        <plugins>
            <plugin>
                <groupId>org.springframework.boot</groupId>
                <artifactId>spring-boot-maven-plugin</artifactId>
            </plugin>
        </plugins>
    </build>

</project>

编写启动类：HystrixDashboardApplication.java

/**
 * 测试步骤:
 * 1. 访问http://localhost:8030/hystrix.stream 可以查看Dashboard
 * 2. 在上面的输入框填入: http://想监控的服务:端口/hystrix.stream进行测试
 * 注意：首先要先调用一下想监控的服务的API，否则将会显示一个空的图表.
 * @author example
 */
@SpringBootApplication
@EnableHystrixDashboard
public class HystrixDashboardApplication {
  public static void main(String[] args) {
    new SpringApplicationBuilder(HystrixDashboardApplication.class).web(true).run(args);
  }
}

配置文件：application.yml

spring:
  application:
    name: hystrix-dashboard
server:
  port: 8030

启动后，访问http://localhost:8030/hystrix.stream 将会看到如下界面：

启动microservice-consumer-movie-feign-hystrix-stream

启动microservice-hystrix-dashboard

此时，我们在输入框中输入http://localhost:8020/actuator/hystrix.stream ，并随意设置一个Title后，点击Monitor Stream按钮，会出现如下界面：

此时我们会看到findById这个API的各种指标。Hystrix Dashboard Wiki上详细说明了图上每个指标的含义，如下图：

此时，我们可以尝试将microservice-provider停止，然后重复访问多次http://localhost:8020/fegin/user/1 （20次以上），会发现断路器状态会变为开启。

大功告成！鼓掌！

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