SpringCloud第二季3-Hystrix

tech2024-11-28  13

Hystrix

1、分布式系统面临的问题

复杂分布式体系结构中的应用程序有数十个依赖关系,每个依赖关系在某些时候将不可避免地损失的。 服务雪崩 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-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。

2、Hystrix是什么?

Hystrix是一个用于处理分布式系统的延迟和容错的开源库, 在分布式系统里,许多依赖不可避免的会调用失败,比如超时、异常等 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。

“断路器”本身是一种开关装置,当某个服务单元发生故障之后,通过断路器的故障监控(类似熔断保险丝),向调用方返回一个符合预期的、可处理的备选响应(FallBack) ,而不是长时间的等待或者抛出调用方无法处理的异常,这样就保证了服务调用方的线程不会被长时间、不必要地占用,从而避免了故障在分布式系统中的蔓延,乃至雪崩。

但是停更了…,不影响先学一波,毕竟设计理论与思想最重要嘛,大家都是抄作业,像阿里的sentinel…会不会我到时候也自研一个哈哈~

服务降级 fallback

服务器忙,请稍后重试,不让客户端等待并返回一个友好提示,fallback 哪些情况会发出降级?

程序运行异常超时服务熔断出发服务降级线程池/信号量打满也会导致服务降级

服务熔断 break

类比保险丝达到最大服务器访问后,直接拒绝访问,拉闸限电,然后调用服务降级的方法并返回友好提示 就是保险丝:服务的降级->进而熔断->恢复调用链路

服务限流 flowlimit

秒杀高并发等操作,严禁一窝蜂的过来拥挤,大家排队,一秒钟N个,有序进行

新建模块cloud-provider-hystrix-payment8001

1、目录结构

2、配置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> <!--引入自定义的api通用包,可用使用Payment支付Entity--> <dependency> <groupId>com.atguigu.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>

3、写application.yml

server: port: 8001 spring: application: name: cloud-provider-hystrix-payment eureka: client: #表示是否将自己注册进EurekaServer默认为true register-with-eureka: true #是否从EurekaServer抓取已有的注册信息,默认为true。单节点无所谓,集群必须设置为true才能配合ribbon使用负载均衡 fetch-registry: true service-url: defaultZone: http://eureka7001.com:7001/eureka # defaultZone: http://eureka7001.com:7001/eureka/,http://eureka7002.com:7002/eureka/

4、主启动类

package com.atguigu.springcloud; import org.springframework.boot.SpringApplication; import org.springframework.boot.autoconfigure.SpringBootApplication; import org.springframework.cloud.client.discovery.EnableDiscoveryClient; @EnableDiscoveryClient @SpringBootApplication public class PaymentHystrixMain8001 { public static void main(String[] args) { SpringApplication.run(PaymentHystrixMain8001.class,args); } }

5、业务类

service层

package com.atguigu.springcloud.service; import org.springframework.stereotype.Service; import java.util.concurrent.TimeUnit; @Service public class PaymentService { public String paymentInfoOK(Integer id){ return "当前线程: "+Thread.currentThread().getName()+"paymentInfo_OK,id:"+id+"\t"+"O(∩_∩)O哈哈~"; } public String paymentInfoTimeOut(Integer id){ int timeout=3; try { TimeUnit.SECONDS.sleep(timeout); } catch (InterruptedException e) { e.printStackTrace(); } return "线程池:"+Thread.currentThread().getName()+" paymentInfo_Timeout,id:"+id+"\t"+"O(∩_∩)O哈哈~"+" 耗时(秒):"+timeout; } }

controller层

package com.atguigu.springcloud.controller; import com.atguigu.springcloud.service.PaymentService; import lombok.extern.slf4j.Slf4j; import org.springframework.beans.factory.annotation.Value; 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; @RestController @Slf4j public class PaymentHystrixController { @Resource private PaymentService paymentService; @Value("${server.port}") private String serverPort; @GetMapping(value = "/payment/hystrix/ok/{id}") public String paymentInfoOK(@PathVariable("id") Integer id){ String result = paymentService.paymentInfoOK(id); log.info("*****result:"+result); return result; } @GetMapping(value = "/payment/hystrix/timeout/{id}") public String paymentInfo_TimeOut(@PathVariable("id") Integer id){ String result = paymentService.paymentInfoTimeOut(id); log.info("*****result:"+result); return result; } }

6、运行代码

正常的方法 http://localhost:8001/payment/hystrix/ok/1 有延迟的方法 http://localhost:8001/payment/hystrix/timeout/1

7、压力测试 JMeter

下载地址 http://jmeter.apache.org/download_jmeter.cgi 运行程序 apache-jmeter-5.2.1\bin\jmeter.bat

启动后,发现不只是超时的服务卡,就连之前ok的服务也会卡的2-3秒

新建模块 cloud-consumer-feign-hystrix-order80

1、目录结构

2、配置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> <!-- 自定义的api通用包 --> <dependency> <groupId>com.atguigu.springcloud</groupId> <artifactId>cloud-api-commons</artifactId> </dependency> <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> <groupId>org.projectlombok</groupId> <artifactId>lombok</artifactId> <optional>true</optional> </dependency> <dependency> <groupId>org.springframework.boot</groupId> <artifactId>spring-boot-devtools</artifactId> <scope>runtime</scope> <optional>true</optional> </dependency> <dependency> <groupId>org.springframework.boot</groupId> <artifactId>spring-boot-starter-test</artifactId> <scope>test</scope> </dependency> </dependencies>

3、写application.yml

server: port: 80 eureka: client: fetch-registry: true service-url: defaultZone: http://eureka7001.com:7001/eureka #设置feign 客户端超时时间(openFeign默认支持ribbon) ribbon: #指的是建立连接后从服务器读取到可用资源所用的时间 ReadTimeout: 5000 #指的是建立连接所用的时间,适用于网络状况正常的情况下,两端连接所用的时间 ConnectTimeout: 5000

4、主启动类

package com.atguigu.springcloud; import org.springframework.boot.SpringApplication; import org.springframework.boot.autoconfigure.SpringBootApplication; import org.springframework.cloud.client.circuitbreaker.EnableCircuitBreaker; import org.springframework.cloud.netflix.hystrix.EnableHystrix; import org.springframework.cloud.openfeign.EnableFeignClients; @SpringBootApplication @EnableFeignClients @EnableHystrix public class OrderHystrixMain80 { public static void main(String[] args) { SpringApplication.run(OrderHystrixMain80.class, args); } }

5、业务类

controller层

package com.atguigu.springcloud.controller; import com.atguigu.springcloud.service.PaymentHystrixService; import lombok.extern.slf4j.Slf4j; import org.springframework.beans.factory.annotation.Autowired; 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; @RestController @Slf4j public class OrderHystrixController { @Resource private PaymentHystrixService paymentHystrixService; @GetMapping(value ="/consumer/payment/hystrix/ok/{id}") public String paymentInfoOK(@PathVariable("id") Integer id){ String result = paymentHystrixService.paymentInfoOK(id); return result; } @GetMapping(value ="/consumer/payment/hystrix/timeout/{id}") public String paymentInfo_TimeOut(@PathVariable("id") Integer id){ String result = paymentHystrixService.paymentInfoTimeOut(id); return result; } }

service层

package com.atguigu.springcloud.service; import org.springframework.cloud.openfeign.FeignClient; import org.springframework.stereotype.Component; import org.springframework.web.bind.annotation.GetMapping; import org.springframework.web.bind.annotation.PathVariable; @Component @FeignClient(value = "CLOUD-PROVIDER-HYSTRIX-PAYMENT") public interface PaymentHystrixService { @GetMapping("/payment/hystrix/ok/{id}") String paymentInfoOK(@PathVariable("id") Integer id); @GetMapping("/payment/hystrix/timeout/{id}") String paymentInfoTimeOut(@PathVariable("id") Integer id); }

6、运行代码

http://localhost/consumer/payment/hystrix/ok/1 http://localhost/consumer/payment/hystrix/timeout/1

服务降级 cloud-provider-hystrix-payment8001

1、业务类

service层

/** * 超时访问,演示降级 */ @HystrixCommand(fallbackMethod = "paymentInfoTimeoutHandler", commandProperties = { @HystrixProperty(name = "execution.isolation.thread.timeoutInMilliseconds", value = "3000") }) public String paymentInfoTimeOut(Integer id){ int timeout=5; // int x = 10 / 0; try { TimeUnit.SECONDS.sleep(timeout); } catch (InterruptedException e) { e.printStackTrace(); } return "线程池:"+Thread.currentThread().getName()+" paymentInfo_Timeout,id:"+id+"\t"+"O(∩_∩)O哈哈~"+" 耗时(秒):"+timeout; } public String paymentInfoTimeoutHandler(Integer id) { return "/(ToT)/调用支付接口超时或异常、\t" + "\t当前线程池名字" + Thread.currentThread().getName(); }

main启动类

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

2、运行代码

http://localhost/consumer/payment/hystrix/timeout/1

服务降级 cloud-consumer-feign-hystrix-order80

1、配置POM

feign: hystrix: enabled: true

2、主启动类

@SpringBootApplication @EnableFeignClients @EnableHystrix public class OrderHystrixMain80 { public static void main(String[] args) { SpringApplication.run(OrderHystrixMain80.class, args); } }

3、业务类

controller层

@RestController @Slf4j public class OrderHystrixController { @Resource private PaymentHystrixService paymentHystrixService; @GetMapping(value ="/consumer/payment/hystrix/ok/{id}") public String paymentInfoOK(@PathVariable("id") Integer id){ return paymentHystrixService.paymentInfoOK(id); } @GetMapping(value ="/consumer/payment/hystrix/timeout/{id}") @HystrixCommand(fallbackMethod = "paymentInfoTimeoutHandler", commandProperties = { @HystrixProperty(name = "execution.isolation.thread.timeoutInMilliseconds", value = "1500") }) public String paymentInfo_TimeOut(@PathVariable("id") Integer id){ return paymentHystrixService.paymentInfoTimeOut(id); } public String paymentInfoTimeoutHandler(Integer id) { return "我是消费者80,对方支付系统繁忙请10秒钟后再试,或者自己运行出错检查自己\t当前线程池名字" + Thread.currentThread().getName(); } }

全局服务降级@DefaultProperties

我们不可能每写一个方法就写一个fallback方法,我们可以同意的处理这些fallback方法 指定全局降级的方法. controller层

@RestController @Slf4j @DefaultProperties(defaultFallback = "paymentInfo_Global_FallbackMethod") public class OrderHystrixController { @GetMapping("/consumer/payment/hystrix/timeout/{id}") @HystrixCommand public String paymentInfo_Timeout(@PathVariable("id") Integer id) { String result = paymentHystrixService.paymentInfo_Timeout(id); return result; } // 下面是全局fallback方法 public String paymentInfo_Global_FallbackMethod() { return "Global异常处理信息,请稍后再试, /(ToT)/"; } }

服务降级 代码解耦 cloud-consumer-feign-hystrix-order80

1、目录结构

2、业务类

service层

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

fallback层

@Component public class PaymentFallbackService implements PaymentHystrixService { @Override public String paymentInfoOK(Integer id) { return "PaymentFallbackService.paymentInfoOK fall back paymentInfo_OK,o(╥﹏╥)o"; } @Override public String paymentInfoTimeOut(Integer id) { return "PaymentFallbackService.paymentInfoTimeOut fall back paymentInfo_OK,o(╥﹏╥)o"; } }

controller层

@RestController @Slf4j public class OrderHystrixController { @Resource private PaymentHystrixService paymentHystrixService; @GetMapping(value = "/consumer/payment/hystrix/ok/{id}") public String paymentInfoOK(@PathVariable("id") Integer id) { return paymentHystrixService.paymentInfoOK(id); } @GetMapping(value = "/consumer/payment/hystrix/timeout/{id}") public String paymentInfoTimeOut(@PathVariable("id") Integer id) { return paymentHystrixService.paymentInfoTimeOut(id); } }

3、运行代码

http://localhost/consumer/payment/hystrix/timeout/1

服务熔断 cloud-provider-hystrix-payment8001

熔断机制概述 熔断机制是应对雪崩效应的一种微服务链路保护机制。当扇出链路的某个微服务出错不可用或者响应时间太长时,会进行服务降级,进而熔断该节点微服务,快速返回错误的相应信息。 当检测到该节点微服务调用正常后,恢复调用链路。

在Spring Cloud框架里,熔断机制通过Hystrix实现。Hystrix会监控微服务间调用的状况。 当失败的调用达到一定阈值,缺省是5秒内20此调用失败,就会启动熔断机制。熔断机制的注解是@HystrixCommand。

1、业务类

controller层

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

service层

// 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"), //请求数达到后才计算 @HystrixProperty(name = "circuitBreaker.sleepWindowInMilliseconds", value = "10000"), //休眠时间窗 @HystrixProperty(name = "circuitBreaker.errorThresholdPercentage", value = "60"), //错误率达到多少跳闸 }) public String paymentCircuitBreaker(@PathVariable("id") Integer id) { if (id < 0) { throw new RuntimeException("****id 不能为负数"); } String serialNumber = IdUtil.simpleUUID(); return Thread.currentThread().getName() + "\t" + "调用成功,流水号:" + serialNumber; }

2、运行代码

正确:http://localhost:8001/payment/circuit/1 错误:http://localhost:8001/payment/circuit/-1

总结:

熔断类型 1、熔断打开:请求不再调用当前服务,内部设置时钟一般为MTTR(平均故障处理时间),当打开时长达到所设时钟则进入半熔断状态 2、熔断关闭:熔断关闭不会对服务进行熔断 3、熔断半开:部分请求根据规则调用当前服务,如果请求成功且符合规则认为当前服务恢复正常,关闭熔断

熔断器在什么情况下开始起作用

// 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"), //请求数达到后才计算 @HystrixProperty(name = "circuitBreaker.sleepWindowInMilliseconds", value = "10000"), //休眠时间窗 @HystrixProperty(name = "circuitBreaker.errorThresholdPercentage", value = "60"), //错误率达到多少跳闸 })

涉及到熔断器的三个重要参数:快找时间窗、请求总数阈值、错误百分比阈值 1、快找时间窗: 断路器确定是否打开需要统计一些请求和错误数据,而统计的时间范围就是快照时间窗,默认为最近的10秒。 2、请求总数阈值: 在快照时间窗内,必须满足请求总数阈值才有资格熔断。默认为20,意味着在10秒内,如果该hystrix命令的调用次数不足20此,即使所有请求都超时或其他原因失败,断路器都不会打开。 3、错误百分比阈值: 当请求总数在快照时间窗内超过了阈值,比如发生了30此调用,如果这30此调用中,有15此发生了超时异常,也就是超过了50%的错误百分比,在默认设定50%阈值情况下,这时候会将断路器打开。

断路器开启或者关闭条件 1、当满足一定阈值的时候(默认10秒内超过20个请求次数) 2、当失败率达到一定的时候(默认10秒内超过50%的请求失败) 3、到达以上阈值,断路器将会开启 4、当开启的时候,所有请求都不会进行转发 5、一段时间之后(默认是5秒),这个时候断路器是半开状态,会让其中一个请求进行转发。如果成功,断路器会关闭,若失败,继续开启,重复4和5

断路器打开之后 1、再有请求调用的时候,将不会调用主逻辑,而是直接调用降级fallback。通过断路器,实现了自动的发现错误并将降级逻辑切换为主逻辑,减少相应延迟的效果。 2、原来的主逻辑要如何恢复呢? 对于这一问题,hystrix也为我们实现了自动回复功能。 当断路器打开,对主逻辑进行熔断之后,hystrix会启动一个休眠时间窗,在这个时间窗内,降级逻辑是临时成为主逻辑。 当休眠时间窗到期,断路器将进入半开状态,释放一次请求道原来的主逻辑上,如果此次请求正常返回,那么断路器将继续闭合,主逻辑恢复,如果这次请求依然有问题,断路器继续进入打开状态,休眠时间窗重新计时。

图形化界面搭建 cloud-consumer-hystrix-dashboard9001

1、工程目录

2、配置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>

3、写application.yml

server: port: 9001

4、主启动类

package com.atguigu.springcloud; import org.springframework.boot.SpringApplication; import org.springframework.boot.autoconfigure.SpringBootApplication; import org.springframework.cloud.netflix.hystrix.dashboard.EnableHystrixDashboard; @SpringBootApplication @EnableHystrixDashboard public class HystrixDashboardMain9001 { public static void main(String[] args) { SpringApplication.run(HystrixDashboardMain9001.class,args); } }

5、访问监控平台

http://localhost:9001/hystrix

6、修改PaymentHystrixMain8001代码

主启动类增加监控代码

@EnableDiscoveryClient @SpringBootApplication @EnableHystrix public class PaymentHystrixMain8001 { public static void main(String[] args) { SpringApplication.run(PaymentHystrixMain8001.class,args); } //主启动类添加代码 /** * 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; } }

7、运行代码

运行项目

访问:http://localhost:9001/hystrix 参数:http://localhost:8001/hystrix.stream T3 访问熔断请求,查看控制台状态 正确:http://localhost:8001/payment/circuit/1 错误:http://localhost:8001/payment/circuit/-1

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