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Spring Cloud Hystrix:服务容错保护
Spring Cloud Hystrix是Spring Cloud中的一个子项目,主要用于服务容错保护;分布式系统中,一个服务的故障或延迟可能会导致整个系统出现问题,为提高系统的稳定性和可用性,Hystrix提供了一种机制来防止这种故障扩散并提供适当的备选方案
Hystrix 简介
Hystrix是Netflix开源的一个用于处理分布式系统延迟和容错的库;主要用于在分布式系统中防止级联故障,提高系统的弹性和稳定性
创建hystrix-service模块
- 依赖导入
<dependency> <groupId>org.springframework.cloud</groupId> <artifactId>spring-cloud-starter-netflix-eureka-client</artifactId> </dependency> <dependency> <groupId>org.springframework.cloud</groupId> <artifactId>spring-cloud-starter-netflix-hystrix</artifactId> </dependency> <dependency> <groupId>org.springframework.boot</groupId> <artifactId>spring-boot-starter-web</artifactId> </dependency>
- 配置application.yml
server: port: 8401 spring: application: name: hystrix-service eureka: client: register-with-eureka: true fetch-registry: true service-url: defaultZone: http://localhost:8001/eureka/ service-url: user-service: http://user-service
- 启动类添加@EnableCircuitBreaker开启Hystrix的断路器功能
@EnableCircuitBreaker @EnableDiscoveryClient @SpringBootApplication public class HystrixServiceApplication { public static void main(String[] args) { SpringApplication.run(HystrixServiceApplication.class, args); }
创建UserHystrixController接口用于调用user-service服务
服务降级演示
@GetMapping("/testFallback/{id}") public CommonResult testFallback(@PathVariable Long id) { return userService.getUser(id); }
- UserService中添加调用方法与服务降级方法,方法上需要添加@HystrixCommand注解
@HystrixCommand(fallbackMethod = "getDefaultUser") public CommonResult getUser(Long id) { return restTemplate.getForObject(userServiceUrl + "/user/{1}", CommonResult.class, id); } public CommonResult getDefaultUser(@PathVariable Long id) { User defaultUser = new User(-1L, "defaultUser", "123456"); return new CommonResult<>(defaultUser); }
@HystrixCommand
@HystrixCommand是Hystrix中的一个注解,用于将Hystrix的断路器功能与具体的方法进行集成;当在方法上添加@HystrixCommand注解时,该方法的执行将由Hystrix进行包装和管理,以提供容错保护和服务降级的能力
- fallbackMethod:指定服务降级处理方法
- ignoreExceptions:忽略某些异常,不发生服务降级
- commandKey:命令名称,用于区分不同的命令
- groupKey:分组名称,Hystrix会根据不同的分组来统计命令的告警及仪表盘信息
- threadPoolKey:线程池名称,用于划分线程池
Hystrix 单个实例监控
Hystrix中,可以通过Hystrix Dashboard来监控单个实例的运行情况;Hystrix Dashboard提供可视化的界面,可以实时监控和查看Hystrix命令的执行情况、断路器的状态、请求的成功和失败等信息
创建hystrix-dashboard模块
- 依赖导入
<dependency> <groupId>org.springframework.cloud</groupId> <artifactId>spring-cloud-starter-netflix-eureka-client</artifactId> </dependency> <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>
- 配置application.yml
server: port: 8501 spring: application: name: hystrix-dashboard eureka: client: register-with-eureka: true fetch-registry: true service-url: defaultZone: http://localhost:8001/eureka/
- 启动类上添加@EnableHystrixDashboard来启用监控功能
@EnableHystrixDashboard @EnableDiscoveryClient @SpringBootApplication public class HystrixDashboardApplication { public static void main(String[] args) { SpringApplication.run(HystrixDashboardApplication.class, args); } }
Hystrix 集群实例监控
Hystrix集群实例监控,使用Netflix Turbine来聚合多个实例的Hystrix数据,并提供集群级别的监控;Netflix Turbine是一个用于监控Hystrix Stream数据的工具,它允许您在分布式系统中查看多个服务实例的断路器状态和指标
创建turbine-service模块
- 依赖导入
<dependency> <groupId>org.springframework.cloud</groupId> <artifactId>spring-cloud-starter-netflix-eureka-client</artifactId> </dependency> <dependency> <groupId>org.springframework.cloud</groupId> <artifactId>spring-cloud-starter-netflix-turbine</artifactId> </dependency> <dependency> <groupId>org.springframework.boot</groupId> <artifactId>spring-boot-starter-actuator</artifactId> </dependency>
- 配置application.yml,添加Turbine相关配置
server: port: 8601 spring: application: name: turbine-service eureka: client: register-with-eureka: true fetch-registry: true service-url: defaultZone: http://localhost:8001/eureka/ turbine: app-config: hystrix-service #指定需要收集信息的服务名称 cluster-name-expression: new String('default') #指定服务所属集群 combine-host-port: true #以主机名和端口号来区分服务
- 启动类上添加@EnableTurbine来启用Turbine相关功能
@EnableTurbine @EnableDiscoveryClient @SpringBootApplication public class TurbineServiceApplication { public static void main(String[] args) { SpringApplication.run(TurbineServiceApplication.class, args); } }
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