springcloud服务降级

Hystrix

概述

雪崩服务

​ 多个微服务之间调用的时候，假设微服务 A 调用微服务 B 和微服务 C,微服务 B 和微服务 C 又调用其它的微服务，这就是所谓的“扇出”。如果扇出的链路上某个微服务的调用响应时间过长或者不可用，对微服务 A 的调用就会占用越来越多的系统资源，进而引起系统崩溃，所谓的“”雪崩效应”
​ 对于高流量的应用来说，单一的后端依赖可能会导致所有服务器上的所有资源都在几秒钟内饱和。比失败更糟糕的是，这些应用程序还可能导致服务之间的延迟增加，备份队列，线程和其他系统资源紧张，导致整个系统发生更多的级联故障。

​ 这些都表示需要对故障和延迟进行隔离和管理，以便单个依赖关系的失败，不能取消整个应用程序或系统。所以，通常当你发现一个模块下的某个实例失败后，这时候这个模块依然还会接收流量，然后这个有问题的模块还调用了其他的模块，这样就会发生级联故障，或者叫雪崩。

是什么

重要概念

1. 服务降级 fallback

   1. ==程序运行异常==
   2. ==超时==
   3. ==服务熔断触发服务降级==
   4. ==线程池打满==

2. 服务熔断 break

1. 接近实时的监控 flowlimit

案例

构建

建 module

• cloud-provider-hystrix-payment8001

pom

<dependencies>
    <!--hystrix-->
    <dependency>
        <groupId>org.springframework.cloud</groupId>
        <artifactId>spring-cloud-starter-netflix-hystrix</artifactId>
    </dependency>
    <!--eureka client-->
    <dependency>
        <groupId>org.springframework.cloud</groupId>
        <artifactId>spring-cloud-starter-netflix-eureka-client</artifactId>
    </dependency>
    <!--web-->
    <dependency>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-web</artifactId>
    </dependency>
    <dependency>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-actuator</artifactId>
    </dependency>
    <dependency><!-- 引入自己定义的api通用包，可以使用Payment支付Entity -->
        <groupId>com.cyt.springcloud</groupId>
        <artifactId>cloud-api-commons</artifactId>
        <version>${project.version}</version>
    </dependency>
    <dependency>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-devtools</artifactId>
        <scope>runtime</scope>
        <optional>true</optional>
    </dependency>
    <dependency>
        <groupId>org.projectlombok</groupId>
        <artifactId>lombok</artifactId>
        <optional>true</optional>
    </dependency>
    <dependency>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-test</artifactId>
        <scope>test</scope>
    </dependency>
</dependencies>

yml

server:
  port: 8001

spring:
  application:
    name: cloud-provider-hystrix-payment

eureka:
  client:
    register-with-eureka: true
    fetch-registry: true
    service-url:
      #defaultZone: http://eureka7001.com:7001/eureka,http://eureka7002.com:7002/eureka
      defaultZone: http://eureka7001.com:7001/eureka

主启动

@SpringBootApplication
@EnableEurekaClient
public class PaymentHystrixMain8001 {
     public static void main(String[] args) {
           SpringApplication.run(PaymentHystrixMain8001.class, args);
      }
}

业务类

• service

@Service
public class PaymentService {
    public String paymentInfo_OK(Integer id) {
        return "线程池:" + Thread.currentThread().getName() + "   paymentInfo_OK,id:" + id + "\t" + "ok";
    }

    public String paymentInfo_TimeOut(Integer id) {
        try {
            TimeUnit.SECONDS.sleep(3);
        } catch (InterruptedException e) {
            e.printStackTrace();
        }
        return "线程池:" + Thread.currentThread().getName() + "   paymentInfo_TimeOut,id:" + id + "\t" + "耗时3s";
    }
}

• controller

@RestController
@Slf4j
public class PaymentController {
    @Resource
    private PaymentService paymentService;

    @Value("${server.port}")
    private String serverPort;

    @GetMapping("/payment/hystrix/ok/{id}")
    public String paymentInfo_OK(@PathVariable("id") Integer id) {
        String res = paymentService.paymentInfo_OK(id);
        log.info("****result:{}", res);
        return res;
    }
}

测试

构建 80

建 module

• cloud-consumer-feign-hystrix-order80

pom

<dependencies>
    <!--openfeign-->
    <dependency>
        <groupId>org.springframework.cloud</groupId>
        <artifactId>spring-cloud-starter-openfeign</artifactId>
    </dependency>
    <!--hystrix-->
    <dependency>
        <groupId>org.springframework.cloud</groupId>
        <artifactId>spring-cloud-starter-netflix-hystrix</artifactId>
    </dependency>
    <!--eureka client-->
    <dependency>
        <groupId>org.springframework.cloud</groupId>
        <artifactId>spring-cloud-starter-netflix-eureka-client</artifactId>
    </dependency>
    <!-- 引入自己定义的api通用包，可以使用Payment支付Entity -->
    <dependency>
        <groupId>com.cyt.springcloud</groupId>
        <artifactId>cloud-api-commons</artifactId>
        <version>${project.version}</version>
    </dependency>
    <!--web-->
    <dependency>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-web</artifactId>
    </dependency>
    <dependency>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-actuator</artifactId>
    </dependency>
    <!--一般基础通用配置-->
    <dependency>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-devtools</artifactId>
        <scope>runtime</scope>
        <optional>true</optional>
    </dependency>
    <dependency>
        <groupId>org.projectlombok</groupId>
        <artifactId>lombok</artifactId>
        <optional>true</optional>
    </dependency>
    <dependency>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-test</artifactId>
        <scope>test</scope>
    </dependency>
</dependencies>

yaml

server:
  port: 80

eureka:
  client:
    register-with-eureka: false
    service-url:
      defaultZone: http://eureka7001.com:7001/eureka/

服务降级

8001 降级

1. service

@Service
public class PaymentService {
    @HystrixCommand(fallbackMethod = "paymentInfo_TimeOutHandler", commandProperties = {
            @HystrixProperty(name="execution.isolation.thread.timeoutInMilliseconds",value="3000") // 3s降级
    })
    public String paymentInfo_TimeOut(Integer id) {
        try {
            TimeUnit.SECONDS.sleep(5);
        } catch (InterruptedException e) {
            e.printStackTrace();
        }
        return "线程池:" + Thread.currentThread().getName() + "   paymentInfo_TimeOut,id:" + id + "\t" + "耗时3s";
    }

    // 降级后调用处理函数
    public String paymentInfo_TimeOutHandler(Integer id) {
        return "线程池:" + Thread.currentThread().getName() + "   系统繁忙，请稍后再试,id:" + id + "\t" + "o(╥﹏╥)o";
    }
}

2. 主启动类

@SpringBootApplication
@EnableEurekaClient
@EnableCircuitBreaker // 服务降级
public class PaymentHystrixMain8001 {
     public static void main(String[] args) {
           SpringApplication.run(PaymentHystrixMain8001.class, args);
      }
}

80 降级

• 一般放在客户端

1. 开启配置

feign:
  hystrix:
    enabled: true

2. 主启动类

• 添加 @EnableHystrix

3. 业务类

@GetMapping("/consumer/payment/hystrix/timeout/{id}")
@HystrixCommand(fallbackMethod = "paymentTimeOutFallbackMethod", commandProperties = {
        @HystrixProperty(name = "execution.isolation.thread.timeoutInMilliseconds", value = "1500")
})
//@HystrixCommand
public String paymentInfo_TimeOut(@PathVariable("id") Integer id) {
    int age = 10 / 0;
    String result = paymentHystrixService.paymentInfo_TimeOut(id);
    return result;
}

public String paymentTimeOutFallbackMethod(@PathVariable("id") Integer id) {
    return "我是消费者80,对方支付系统繁忙请10秒钟后再试或者自己运行出错请检查自己,o(╥﹏╥)o";
}

问题处理

==@DefaultProperties==

• 统一处理 默认方法
  • 写在类名上面
  • 解决代码耦合度高的问题

• controller

@RestController
@Slf4j
@DefaultProperties(defaultFallback = "payment_Global_FallbackMethod")
public class OrderHystrixController {
    // 下面是全局fallback方法
    public String payment_Global_FallbackMethod() {
        return "Global异常处理信息，请稍后再试，/(ㄒoㄒ)/~~";
    }
}

==@FeignClient==

• 避免混乱

service 包下

1. 接口

@Component
@FeignClient(value = "CLOUD-PROVIDER-HYSTRIX-PAYMENT", fallback = PaymentFallbackService.class) // 指定下面类
public interface PaymentHystrixService {
    @GetMapping("/payment/hystrix/ok/{id}")
    public String paymentInfo_OK(@PathVariable("id") Integer id);

    @GetMapping("/payment/hystrix/timeout/{id}")
    public String paymentInfo_TimeOut(@PathVariable("id") Integer id);
}

2. 实现类

@Component
public class PaymentFallbackService implements PaymentHystrixService // 继承上面接口
{
    @Override
    public String paymentInfo_OK(Integer id)
    {
        return "-----PaymentFallbackService fall back-paymentInfo_OK ,o(╥﹏╥)o";
    }

    @Override
    public String paymentInfo_TimeOut(Integer id)
    {
        return "-----PaymentFallbackService fall back-paymentInfo_TimeOut ,o(╥﹏╥)o";
    }
}

yml 配置

feign:
  hystrix:
    enabled: true

服务熔断

概念

业务类

• service

//===服务熔断
@HystrixCommand(fallbackMethod = "paymentCircuitBreaker_fallback",commandProperties = {
        @HystrixProperty(name = "circuitBreaker.enabled",value = "true"),// 是否开启断路器
        @HystrixProperty(name = "circuitBreaker.requestVolumeThreshold",value = "10"),// 请求次数
        @HystrixProperty(name = "circuitBreaker.sleepWindowInMilliseconds",value = "10000"), // 时间窗口期
        @HystrixProperty(name = "circuitBreaker.errorThresholdPercentage",value = "60"),// 失败率达到多少后跳闸
})
public String paymentCircuitBreaker(@PathVariable("id") Integer id)
{
    if(id < 0)
    {
        throw new RuntimeException("******id 不能负数");
    }
    String serialNumber = IdUtil.simpleUUID();

    return Thread.currentThread().getName()+"\t"+"调用成功，流水号: " + serialNumber;
}
public String paymentCircuitBreaker_fallback(@PathVariable("id") Integer id)
{
    return "id 不能负数，请稍后再试，/(ㄒoㄒ)/~~   id: " +id;
}

• controller

//====服务熔断
@GetMapping("/payment/circuit/{id}")
public String paymentCircuitBreaker(@PathVariable("id") Integer id)
{
    String result = paymentService.paymentCircuitBreaker(id);
    log.info("****result: "+result);
    return result;
}

• ==开启关闭条件==

服务限流

• 暂时不学

服务监控 HystrixDashboard

建 module

• cloud-consumer-hystrix-dashboard9001

pom

<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-actuator</artifactId>
    </dependency>

    <dependency>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-devtools</artifactId>
        <scope>runtime</scope>
        <optional>true</optional>
    </dependency>
    <dependency>
        <groupId>org.projectlombok</groupId>
        <artifactId>lombok</artifactId>
        <optional>true</optional>
    </dependency>
    <dependency>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-test</artifactId>
        <scope>test</scope>
    </dependency>
</dependencies>

yaml

server:
  port: 9001

启动类

@SpringBootApplication
@EnableHystrixDashboard
public class HystrixDashboardMain9001
{
    public static void main(String[] args) {
            SpringApplication.run(HystrixDashboardMain9001.class, args);
    }
}

9001 监控 8001

1. 8001 启动类

@SpringBootApplication
@EnableEurekaClient
@EnableCircuitBreaker
public class PaymentHystrixMain8001
{
    public static void main(String[] args) {
            SpringApplication.run(PaymentHystrixMain8001.class, args);
    }


    /**
     *此配置是为了服务监控而配置，与服务容错本身无关，springcloud升级后的坑
     *ServletRegistrationBean因为springboot的默认路径不是"/hystrix.stream"，
     *只要在自己的项目里配置上下面的servlet就可以了
     */
    @Bean
    public ServletRegistrationBean getServlet() {
        HystrixMetricsStreamServlet streamServlet = new HystrixMetricsStreamServlet();
        ServletRegistrationBean registrationBean = new ServletRegistrationBean(streamServlet);
        registrationBean.setLoadOnStartup(1);
        registrationBean.addUrlMappings("/hystrix.stream");
        registrationBean.setName("HystrixMetricsStreamServlet");
        return registrationBean;
    }
}

2. 填入地址 http://localhost:8001/hystrix.stream

3. 结果