hystrix
hystrix工作原理

1.Hystrix

pom

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

采用的是消费端去调用服务端(注册中心eureka)：
openfeign pom:

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

@Component
@FeignClient(value = "CLOUD-PROVIDER-HYSTRIX-PAYMENT")
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);
}

回调类：

/** * 下面方法一一对应一个fallback方法 */
@Component
public class PaymentFallbackService implements PaymentHystrixService { 
    @Override
    public String paymentInfo_OK(Integer id) { 
        return "-----PaymentFallbackService fall back-paymentInfo_OK , (┬＿┬)";
    }
    @Override
    public String paymentInfo_TimeOut(Integer id) { 
        return "-----PaymentFallbackService fall back-paymentInfo_TimeOut , (┬＿┬)";
    }
}

controller：

@RestController
@Slf4j
public class OrderHystrixController { 
    @Resource
    private PaymentHystrixService paymentHystrixService;
    @Value("${server.port}")
    private String serverPort;
    @GetMapping("/consumer/payment/hystrix/ok/{id}")
    @HystrixCommand
    public String paymentInfo_OK(@PathVariable("id") Integer id) { 
        String result = paymentHystrixService.paymentInfo_OK(id);
        log.info("*******result:" + result);
        return result;
    }
    @GetMapping("/consumer/payment/hystrix/timeout/{id}")
    public String paymentInfo_TimeOut(@PathVariable("id") Integer id) { 
        String result = paymentHystrixService.paymentInfo_TimeOut(id);
        return result;
    }
}

服务降级

设置服务提供方的超时兜底方法

配置 超时的兜底方法paymentInfo_TimeOutHandler:
只要是服务不可用了超时或者抛出异常都可以调用兜底方法

//失败
    @HystrixCommand(fallbackMethod = "paymentInfo_TimeOutHandler", commandProperties = { 
            @HystrixProperty(name = "execution.isolation.thread.timeoutInMilliseconds", value = "3000")  //3秒钟以内就是正常的业务逻辑
    })
    public String paymentInfo_TimeOut(Integer id) { 
        // int timeNumber = 5;
        int age = 10 / 0;
        // try { TimeUnit.SECONDS.sleep(timeNumber); }catch (Exception e) {e.printStackTrace();}
        //return "线程池："+Thread.currentThread().getName()+" paymentInfo_TimeOut,id： "+id+"\t"+"呜呜呜"+" 耗时(秒)"+timeNumber;
        return "线程池：" + Thread.currentThread().getName() + " paymentInfo_TimeOut,id： " + id + "\t" + "呜呜呜" + " 耗时(秒)";
    }
    //超时兜底方法
    public String paymentInfo_TimeOutHandler(Integer id) { 
        return "线程池：" + Thread.currentThread().getName() + " 系统繁忙, 请稍候再试 ,id： " + id + "\t" + "哭了哇呜";
    }

主启动类激活熔断功能：

测试:

消费方降级保护：

yml

feign:
  hystrix:
    enabled: true #如果处理自身的容错就开启。开启方式与生产端不一样。

controller添加超时兜底方法：

@GetMapping("/consumer/payment/hystrix/timeout/{id}")
    @HystrixCommand(fallbackMethod = "paymentTimeOutFallbackMethod",
            commandProperties = { @HystrixProperty(name = "execution.isolation.thread.timeoutInMilliseconds", value = "1500")  //3秒钟以内就是正常的业务逻辑 80只等1.5秒
            })
    public String paymentInfo_TimeOut(@PathVariable("id") Integer id) { 
        String result = paymentHystrixService.paymentInfo_TimeOut(id);
        return result;
    }
    //兜底方法
    public String paymentTimeOutFallbackMethod(@PathVariable("id") Integer id) { 
        return "我是消费者80,对付支付系统繁忙请10秒钟后再试或者自己运行出错请检查自己,(┬＿┬)";
    }

全局兜底方法

注意：@HystrixCommond没有特别指明用全局兜底方法

//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,(┬＿┬)";
    }

在Service层配置统一降级

@Component
@FeignClient(value = "CLOUD-PROVIDER-HYSTRIX-PAYMENT",fallback =  PaymentFallbackService.class) //指名方法对应兜底方法
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);
}
/** * 下面方法一一对应一个fallback方法 */
@Component
public class PaymentFallbackService implements PaymentHystrixService { 
    @Override
    public String paymentInfo_OK(Integer id) { 
        return "-----PaymentFallbackService fall back-paymentInfo_OK , (┬＿┬)";
    }
    @Override
    public String paymentInfo_TimeOut(Integer id) { 
        return "-----PaymentFallbackService fall back-paymentInfo_TimeOut , (┬＿┬)";
    }
}

服务熔断

存在逐渐恢复链路过程是熔断的主要特性，即能够恢复

服务提供方

/** * ====服务熔断 * * @param id * @return */
    @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"),  //时间范围
            @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，请稍候再试,(┬＿┬)/~~ id: " + id;
    }

服务限流

@HystrixCommand(fallbackMethod = "helloError",
            commandProperties = { 
                    @HystrixProperty(name = "execution.isolation.strategy", value = "THREAD"),
                    @HystrixProperty(name = "execution.isolation.thread.timeoutInMilliseconds", value = "1000"),
                    @HystrixProperty(name = "circuitBreaker.enabled", value = "true"),
                    @HystrixProperty(name = "circuitBreaker.requestVolumeThreshold", value = "2")},
            threadPoolProperties = { 
                    @HystrixProperty(name = "coreSize", value = "5"),
                    @HystrixProperty(name = "maximumSize", value = "5"),
                    @HystrixProperty(name = "maxQueueSize", value = "10")
            })

How it works？