SpringCloud

技术栈

服务注册与发现

EUREKA(停更),Zookeeper,Consul,Nocos

服务调用

RIBBON(NETFLIX网飞), LoadBalancer, FELGN(停更) , OpenFeign

服务熔断降级

HYSTRIX (不推荐) ,resilience4j (国外推荐) ,sentienl (国内推荐)

服务网关

ZUUL (不推荐) , gateWay

服务分布配置

SpringCloud Config (不推荐) , Nocos

服务总线

Bus (不推荐) , Nocos

Hystrix

是什么?

用于处理分布式系统的延迟和容差的开源库
在分布式系统里,许多依赖不可避免的回调用失败,超时,异常,Hystrix能够保证在一个依赖出问题的情况下，不会导致整体服务失败,避免级联故障,以提高分布式系统的弹性。

能干什么?

服务降级
服务熔断
服务限流

服务降级?

服务忙,不让客户端等待并立即返回一个友好的提示 fallback
什么情况下会发生服务降级?

程序运行错误

超时

服务熔断触发服务降级

线程池/信号量也会导致服务降级

服务熔断?

保险丝服务的降级->进而熔断->恢复调用链路

服务限流?

高并发操作

服务降级

服务端Hystrix案例

@HystrixCommand
@EnableCircuitBreaker

pom.xml

     <!--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>

application.yml

server:port: 8001
spring:application:name: cloud-provider-hystrix-payment
eureka:client:fetch-registry: trueregister-with-eureka: trueservice-url:defaultZone: http://localhost:7001/eureka/

PaymentService

@HystrixCommand(fallbackMethod = “错误时调用的方法”,commandProperties = {
@HystrixProperty(name = “execution.isolation.thread.timeoutInMilliseconds”, value = “3000”)//只等待3秒
})

@Service
public class PaymentService {public String paymentInfo_ok(Integer id){return "线程池:"+Thread.currentThread().getName()+"paymentInfo_ok:"+ UUID.randomUUID().toString()+"--id:"+id+"O(∩_∩)O哈哈~";}@HystrixCommand(fallbackMethod = "paymentInfo_TimerOutHandler",commandProperties = {@HystrixProperty(name = "execution.isolation.thread.timeoutInMilliseconds", value = "3000")//只等待3秒})public String paymentInfo_fail(Integer id){//        int i = 4/0;try {TimeUnit.SECONDS.sleep(5);} catch (InterruptedException e) {e.printStackTrace();}return "线程池:"+Thread.currentThread().getName()+"paymentInfo_fail:"+ UUID.randomUUID().toString()+"--id:"+id+"┭┮﹏┭┮";}public String paymentInfo_TimerOutHandler(Integer id){return "超时或异常";}
}

PaymentController

@RestController
@Slf4j
public class PaymentController {@Autowiredprivate PaymentService paymentService;@GetMapping("/payment/hystrix/ok/{id}")public String ok(@PathVariable("id") Integer id){String s = paymentService.paymentInfo_ok(id);log.info("***********ok");return s;}@GetMapping("/payment/hystrix/time_out/{id}")public String fail(@PathVariable("id") Integer id){String s = paymentService.paymentInfo_fail(id);log.info("***********fail");return s;}}

主启动

@EnableCircuitBreaker

@SpringBootApplication
@EnableEurekaClient
@EnableCircuitBreaker
public class MainProviderHystrixPayment8001 {public static void main(String[] args) {SpringApplication.run(MainProviderHystrixPayment8001.class,args);}
}

客户端

application.yml

server:port: 80
spring:application:name: cloud-consumer-hystrix-order
eureka:client:fetch-registry: trueregister-with-eureka: trueservice-url:defaultZone: http://eureka7001.com:7001/eureka#      defaultZone: http://eureka7001.com:7001/eureka,http://eureka7002.com:7002/eureka  # 集群版
feign:hystrix:enabled: true

MainHystrixOrder80

@SpringBootApplication
@EnableFeignClients
@EnableEurekaClient
@EnableHystrix
public class MainHystrixOrder80 {public static void main(String[] args) {SpringApplication.run(MainHystrixOrder80.class,args);}
}

PaymentHystrixService

@Component
@FeignClient(value = "CLOUD-PROVIDER-HYSTRIX-PAYMENT",fallback = PaymentFallbackService.class)
public interface PaymentHystrixService {/*** 正常访问** @param id* @return*/@GetMapping("/payment/hystrix/ok/{id}")public String ok(@PathVariable("id") Integer id);/*** 超时访问** @param id* @return*/@GetMapping("/payment/hystrix/time_out/{id}")public String fail(@PathVariable("id") Integer id);
}

OrderHystrixController

@RestController
@Slf4j
public class OrderHystrixController {@Resourceprivate PaymentHystrixService paymentHystrixService;@GetMapping("/consumer/payment/hystrix/ok/{id}")public String paymentInfo_OK(@PathVariable("id") Integer id){return paymentHystrixService.ok(id);}/*** 超时访问* @param id* @return*/@GetMapping("/consumer/payment/hystrix/timeout/{id}")@HystrixCommand(fallbackMethod = "paymentTimeOutFallbackMethod", commandProperties = {@HystrixProperty(name = "execution.isolation.thread.timeoutInMilliseconds", value = "1500")})public String paymentInfo_TimeOut(@PathVariable("id") Integer id) {//        int age = 10/0; //方法前挂了，跟后面挂了两种return paymentHystrixService.fail(id);}public String paymentTimeOutFallbackMethod(@PathVariable("id") Integer id) {return "我是消费者80,对方支付系统繁忙请10秒种后再试或者自己运行出错请检查自己,o(╥﹏╥)o";}
}

解决代码膨胀

@DefaultProperties(defaultFallback = “payment_Global_FallbackMethod”)
@HystrixCommand //没有特别指明就用统一的

package com.wu.scho.controller;import com.netflix.hystrix.contrib.javanica.annotation.DefaultProperties;
import com.netflix.hystrix.contrib.javanica.annotation.HystrixCommand;
import com.netflix.hystrix.contrib.javanica.annotation.HystrixProperty;
import com.wu.scho.service.PaymentHystrixService;
import lombok.extern.slf4j.Slf4j;
import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.PathVariable;
import org.springframework.web.bind.annotation.RestController;import javax.annotation.Resource;/*** @program: IClould2020Wu* @author: Mr-Jies* @create: 2020-05-16 20:43**/
@RestController
@Slf4j
@DefaultProperties(defaultFallback = "payment_Global_FallbackMethod")
public class OrderHystrixController {@Resourceprivate PaymentHystrixService paymentHystrixService;@GetMapping("/consumer/payment/hystrix/ok/{id}")public String paymentInfo_OK(@PathVariable("id") Integer id){return paymentHystrixService.ok(id);}/*** 超时访问* @param id* @return*/@GetMapping("/consumer/payment/hystrix/timeout/{id}")/* @HystrixCommand(fallbackMethod = "paymentTimeOutFallbackMethod", commandProperties = {@HystrixProperty(name = "execution.isolation.thread.timeoutInMilliseconds", value = "1500")})*/@HystrixCommand  //没有特别指明就用统一的public String paymentInfo_TimeOut(@PathVariable("id") Integer id) {//        int age = 10/0; //方法前挂了，跟后面挂了两种return paymentHystrixService.fail(id);}public String paymentTimeOutFallbackMethod(@PathVariable("id") Integer id) {return "我是消费者80,对方支付系统繁忙请10秒种后再试或者自己运行出错请检查自己,o(╥﹏╥)o";}//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)/~~";}}

统一为接口里面的方法进行异常处理

fallback

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

正常访问

8001服务器挂了,客户端降级处理

服务熔断

是什么?

但某一微服务出错或者不可用时,会进行降级,进而就熔断了微服务的调用,但当检测到节点调用响应正常后,会恢复链路

服务端

PaymentService

@HystrixProperty(name = “circuitBreaker.enabled”, value = “true”),// 是否开启断路器
@HystrixProperty(name = “circuitBreaker.requestVolumeThreshold”, value = “10”),// 请求峰值
@HystrixProperty(name = “circuitBreaker.sleepWindowInMilliseconds”, value = “10000”),// 时间窗口期/时间范围
@HystrixProperty(name = “circuitBreaker.errorThresholdPercentage”, value = “60”)// 失败率达到多少后跳闸

    @HystrixCommand(fallbackMethod = "paymentInfo_scoreHandler",commandProperties = {@HystrixProperty(name = "circuitBreaker.enabled", value = "true"),// 是否开启断路器@HystrixProperty(name = "circuitBreaker.requestVolumeThreshold", value = "10"),// 请求峰值@HystrixProperty(name = "circuitBreaker.sleepWindowInMilliseconds", value = "10000"),// 时间窗口期/时间范围@HystrixProperty(name = "circuitBreaker.errorThresholdPercentage", value = "60")// 失败率达到多少后跳闸})public String paymentInfo_score(Integer id){if (id<0){throw new RuntimeException("id,不能为负数");}String s = UUID.randomUUID().toString();return "线程池:"+Thread.currentThread().getName()+"paymentInfo_fail:"+ UUID.randomUUID().toString()+"--id:"+id+"O(∩_∩)O哈哈~";}public String paymentInfo_scoreHandler(Integer id){return "超时或异常";}

配置属性的来源 HystrixCommandProperties

PaymentController

    @GetMapping("/payment/hystrix/score/{id}")public String paymentInfo_score(@PathVariable("id") Integer id){String s = paymentService.paymentInfo_score(id);log.info("----------::"+s);return s;}

监控窗口

pom.xml

<!--hystrix dashboard--><dependency><groupId>org.springframework.cloud</groupId><artifactId>spring-cloud-starter-netflix-hystrix-dashboard</artifactId></dependency><!--监控--><dependency><groupId>org.springframework.boot</groupId><artifactId>spring-boot-starter-actuator</artifactId></dependency>

在主启动类上加@EnableHystrixDashboard

注意:新版本Hystrix需要在主启动Mainpystrix8001中指定监控路径

/*** @program: IClould2020Wu* @author: Mr-Jies* @create: 2020-05-16 20:17**/@SpringBootApplication
@EnableEurekaClient
@EnableCircuitBreaker
public class MainProviderHystrixPayment8001 {public static void main(String[] args) {SpringApplication.run(MainProviderHystrixPayment8001.class,args);}/*** 此配置是为了服务监控而配置，与服务容错本身无观，springCloud 升级之后的坑* ServletRegistrationBean因为springboot的默认路径不是/hystrix.stream* 只要在自己的项目中配置上下面的servlet即可* @return*/@Beanpublic ServletRegistrationBean getServlet(){HystrixMetricsStreamServlet streamServlet = new HystrixMetricsStreamServlet();ServletRegistrationBean<HystrixMetricsStreamServlet> registrationBean = new ServletRegistrationBean<>(streamServlet);registrationBean.setLoadOnStartup(1);registrationBean.addUrlMappings("/hystrix.stream");registrationBean.setName("HystrixMetricsStreamServlet");return registrationBean;}
}

Hystrix的三种状态

1、closed：请求正常时，不使用熔断器；

2、open：统计请求的失败比例，达到阀值时，打开熔断器，请求被降级处理；延时一段时候后（默认休眠时间是5S）会进入halfopen状态；默认失败比例阀值是50%，请求次数最少不低于20次；

3、halfopen：在进入该状态后会放入部分请求；判断请求是否成功，不成功，进入open状态，重新计时，进入halfopen状态；成功，进入closed状态，

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SpringCloud(3)--服务熔断降级

SpringCloud

技术栈

Hystrix

服务降级

服务端Hystrix案例

pom.xml

application.yml

PaymentService

PaymentController

主启动

客户端

application.yml

MainHystrixOrder80

PaymentHystrixService

OrderHystrixController

解决代码膨胀

统一为接口里面的方法进行异常处理

服务熔断

服务端

PaymentService

PaymentController

监控窗口

pom.xml

在主启动类上加@EnableHystrixDashboard

注意:新版本Hystrix需要在主启动Mainpystrix8001中指定监控路径

Hystrix的三种状态

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