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spring cloud Feign+Hystrix实现Fallback多级降级,Timeout降级,Request Cache减压

互联网 diligentman 6天前 5次浏览

Hystrix介绍

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),而不长时间的等待或者抛出调用方法无法处理的异常,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。

github地址:https://github.com/Netflix/Hystrix

服务降级

所谓降级,就是当某个服务出现异常之后,服务器将不再被调用,此时服务端可以自己准备一个本地的fallback回调,返回一个缺省值。 这样做,虽然服务水平下降,但好歹可用,比直接挂掉要强,当然这也要看适合的业务场景。

可能出现服务降级的情况:

  1. 程序运行异常
  2. 服务超时
  3. 服务熔断出发服务降级
  4. 线程池/信号量打满也会导致服务降级

版本说明

Java : 1.8
Spring Boot : 2.1.5.RELEASE
Spring Cloud: Greenwich.SR1

项目说明

eureka-server:eureka服务中心
feign-client :feign生产者
feign-client-intf:feign接口提供者
hystrix-fallback:hystrix降级demo

eureka-server 前面文章已经提供不在粘贴出来了

feign-client-intf:feign接口提供者

pom.xml

 <dependencies>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-web</artifactId>
        </dependency>

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

server接口提供

@FeignClient("feign-client")
public interface IService {

    @GetMapping("/sayHi")
    public String sayHi();

    @PostMapping("/sayHi")
    public Friend sayHiPost(@RequestBody Friend friend);

    @GetMapping("/retry")
    public String retry(@RequestParam(name = "timeout") int timeout);

    @GetMapping("/error")
    public String error();

}

Friend实体类

@Data
public class Friend {

    private String name;

    private String port;

}

feign-client :feign生产者

pom.xml

dependencies>
    <dependency>
        <groupId>org.springframework.cloud</groupId>
        <artifactId>spring-cloud-starter-netflix-eureka-client</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>com.imooc</groupId>
        <artifactId>feign-client-intf</artifactId>
        <version>${project.version}</version>
    </dependency>

</dependencies>

application.properties

spring.application.name=feign-client
server.port=40006


eureka.client.serviceUrl.defaultZone=http://localhost:20000/eureka/

Controller

@RestController
public class Controller implements IService {
    Logger log = LoggerFactory.getLogger(Controller.class);

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


    @GetMapping("/sayHi2")
    public String sayHi2() {
        return "This is " + port;
    }

    @Override
    public String sayHi() {
        return "This is " + port;
    }

    @Override

    public Friend sayHiPost(@RequestBody Friend friend) {
        log.info("You are " + friend.getName());
        friend.setPort(port);
        return friend;
    }

    @Override
    public String retry(@RequestParam(name = "timeout") int timeout) {
        System.out.println("timeout"+timeout);
        while (--timeout >= 0) {
            try {
                Thread.sleep(1000);
            } catch (InterruptedException e) {
            }
        }
        log.info("retry " + port);
        return port;
    }

    @Override
    public String error() {
        throw new RuntimeException("black sheep");
    }
}

FeignClientApplication启动类

@EnableDiscoveryClient
@SpringBootApplication
public class FeignClientApplication {

    public static void main(String[] args) {
        new SpringApplicationBuilder(FeignClientApplication.class)
                .web(WebApplicationType.SERVLET)
                .run(args);
    }

}

hystrix-fallback:hystrix降级demo

spring cloud Feign+Hystrix实现Fallback多级降级,Timeout降级,Request Cache减压

pom.xml

dependencies>

        <dependency>
            <groupId>org.springframework.cloud</groupId>
            <artifactId>spring-cloud-starter-netflix-eureka-client</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>com.imooc</groupId>
            <artifactId>feign-client-intf</artifactId>
            <version>${project.version}</version>
        </dependency>

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

application.properties

spring.application.name=hystrix-consumer
server.port=50001
spring.main.allow-bean-definition-overriding=true
eureka.client.serviceUrl.defaultZone=http://localhost:20000/eureka/

# 开启Feign下面的Hystrix功能
feign.hystrix.enabled=true
# 是否开启服务降级
hystrix.command.default.fallback.enabled=true

# 全局超时
hystrix.command.default.execution.timeout.enabled=true
# 超时时间
hystrix.command.default.execution.isolation.thread.timeoutInMilliseconds=3000
# 超时以后终止线程
hystrix.command.default.execution.isolation.thread.interruptOnTimeout=true
# 取消的时候终止线程
hystrix.command.default.execution.isolation.thread.interruptOnFutureCancel=true
# hystrix.command.MyService#retry(int).execution.isolation.thread.timeoutInMilliseconds=3000



# 每台机器最大重试次数
feign-client.ribbon.MaxAutoRetries=0
# 可以再重试几台机器
feign-client.ribbon.MaxAutoRetriesNextServer=0
# 连接超时
feign-client.ribbon.ConnectTimeout=1000
# 业务处理超时
feign-client.ribbon.ReadTimeout=8000
# 在所有HTTP Method进行重试
feign-client.ribbon.OkToRetryOnAllOperations=false

Controller

@RestController
public class Controller {

    @Autowired
    private MyService myService;

    @Autowired
    private RequestCacheService requestCacheService;

    @GetMapping("/fallback")
    public String fallback() {
        return myService.error();
    }

    @GetMapping("/timeout")
    public String timeout(Integer timeout) {
        System.out.println(timeout);
        return myService.retry(timeout);
    }

    @GetMapping("/timeout2")
    @HystrixCommand(
            fallbackMethod = "timeoutFallback",
            commandProperties = {
               @HystrixProperty(name = "execution.isolation.thread.timeoutInMilliseconds", value="3000")
            }
    )
    public String timeout2(Integer timeout) {
        return myService.retry(timeout);
    }

    public String timeoutFallback(Integer timeout) {
        return "success";
    }

    @GetMapping("/cache")
    public Friend cache(String name) {
        @Cleanup HystrixRequestContext context =
                HystrixRequestContext.initializeContext();

        Friend friend = requestCacheService.requestCache(name);
        friend = requestCacheService.requestCache(name);
        return friend;
    }

}

MyService

@FeignClient(name = "feign-client", fallback = Fallback.class)
public interface MyService extends IService {

}

Fallback 降级处理类

@Slf4j
@Component
public class Fallback implements MyService {

    @Override
    //@HystrixCommand(fallbackMethod = "fallback2")
    public String error() {
        log.info("Fallback: I'm not a black sheep any more");
        throw new RuntimeException("first fallback");
    }

    @HystrixCommand(fallbackMethod = "fallback3")
    public String fallback2() {
        log.info("fallback again");
        throw new RuntimeException("fallback again");
    }

    public String fallback3() {
        log.info("fallback again and again");
        return "success";
    }


    @Override
    public String sayHi() {
        return null;
    }

    @Override
    public Friend sayHiPost(@RequestBody Friend friend) {
        return null;
    }

    @Override
    public String retry(@RequestParam(name = "timeout") int timeout) {
        return "You are late !";
    }

}

RequestCacheService Request Cache减压

@Slf4j
@Service
public class RequestCacheService {

    @Autowired
    private MyService service;

    @CacheResult
    @HystrixCommand(commandKey = "cacheKey")
    public Friend requestCache(@CacheKey String name) {
        log.info("request cache " + name);
        Friend friend = new Friend();
        friend.setName(name);
        friend = service.sayHiPost(friend);
        log.info("after requesting cache " + name);
        return friend;
    }

}

HystrixFallbackApplication启动类

@EnableDiscoveryClient
@SpringBootApplication
@EnableFeignClients
@EnableCircuitBreaker
public class HystrixFallbackApplication {

    public static void main(String[] args) throws NoSuchMethodException {
        new SpringApplicationBuilder(HystrixFallbackApplication.class)
                .web(WebApplicationType.SERVLET)
                .run(args);

//        System.out.println(Feign.configKey(MyService.class,
//                MyService.class.getMethod("retry", int.class)));
    }

}

测试

依次启动:
eureka-server:eureka服务中心
feign-client :feign生产者
hystrix-fallback:hystrix降级demo
spring cloud Feign+Hystrix实现Fallback多级降级,Timeout降级,Request Cache减压

Fallback多级降级测试

测试步骤:
1.通过postman来调用hystrix-fallback fallback接口
spring cloud Feign+Hystrix实现Fallback多级降级,Timeout降级,Request Cache减压

2.然后通过feign来调用feign-client的error接口来获取一个异常看看能不能降级。spring cloud Feign+Hystrix实现Fallback多级降级,Timeout降级,Request Cache减压
3.多级降级处理
spring cloud Feign+Hystrix实现Fallback多级降级,Timeout降级,Request Cache减压
postman 放回的结果,然后分析一下结果。
spring cloud Feign+Hystrix实现Fallback多级降级,Timeout降级,Request Cache减压
在feign-client当中 抛出了一个RuntimeException的错误。然后会被hystrix进行降级处理。
spring cloud Feign+Hystrix实现Fallback多级降级,Timeout降级,Request Cache减压
我们再去hystrix-fallback的控制台看看有没有被降级。
spring cloud Feign+Hystrix实现Fallback多级降级,Timeout降级,Request Cache减压
这三条输出对应的就是之前多级处理的打印的结果说明 多级降级是成功的。

Timeout降级测试

1.设置全局的超时时间 超过时间就会Timeout降级 这里我是设置的3s
spring cloud Feign+Hystrix实现Fallback多级降级,Timeout降级,Request Cache减压

2通过postman来调用hystrix-fallback timeout接口
spring cloud Feign+Hystrix实现Fallback多级降级,Timeout降级,Request Cache减压
3.然后通过feign来调用feign-client的retry接口让线程sleep相应的时间
spring cloud Feign+Hystrix实现Fallback多级降级,Timeout降级,Request Cache减压
4.如果没有超时就会retrun 出feign-clien端口号 超时了的话就会进入timeout降级处理类
spring cloud Feign+Hystrix实现Fallback多级降级,Timeout降级,Request Cache减压
5.先测试2s 没有超时的结果
spring cloud Feign+Hystrix实现Fallback多级降级,Timeout降级,Request Cache减压

6.先然后测试3s 超时的结果
spring cloud Feign+Hystrix实现Fallback多级降级,Timeout降级,Request Cache减压

Request Cache减压测试

1.通过postman来调用hystrix-fallback cache接口,然后接口里面连续调用了 两次requestCacheService.requestCache(name);
如果打印两遍相同的log说明没有被缓存到本地,解压失败。
如果只打印一遍og说明有被缓存到本地,解压成功。
spring cloud Feign+Hystrix实现Fallback多级降级,Timeout降级,Request Cache减压
requestCacheService.requestCache
spring cloud Feign+Hystrix实现Fallback多级降级,Timeout降级,Request Cache减压
调用接口
spring cloud Feign+Hystrix实现Fallback多级降级,Timeout降级,Request Cache减压
只打印了一遍Log说明解压成功
spring cloud Feign+Hystrix实现Fallback多级降级,Timeout降级,Request Cache减压
以上有问题请指出来!交流学习


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