10.hystrix circuit breaker

Study B Standing still, Mr. Zhou Yang of Silicon Valley SpringCloud The lecture notes

1. summary

1.1 The problem of distributed system

1.2. What is it?

1.3. What can I do?

service degradation
Service failure
Service restriction
Close to real-time monitoring

github Address ：https://github.com/Netflix/Hystrix/wiki/How-To-Use

Hystrix Official announcement , Stop and improve dimension , Passive repair bugs, No longer accept merge requests , No more releases

2.hystrix Case study

2.1 newly build cloud-provider-hystrix-payment8001

2.1.1 Change pom

<dependencies>
        <!-- newly added hystrix-->
        <dependency>
            <groupId>org.springframework.cloud</groupId>
            <artifactId>spring-cloud-starter-netflix-hystrix</artifactId>
        </dependency>
        <dependency>
            <groupId>org.springframework.cloud</groupId>
            <artifactId>spring-cloud-starter-netflix-eureka-client</artifactId>
        </dependency>

        <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-starter-web</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>

2.1.2 Change yml

server:
  port: 8001

eureka:
  client:
    register-with-eureka: true    # I don't register myself with the registry 
    fetch-registry: true   # Say you're the registry , The responsibility is to maintain service instances , There's no need to retrieve Services 
    service-url:
      # defaultZone: http://eureka7002.com:7002/eureka/ # Set up with eureka server Both the interactive address query service and the registration service need to rely on this address 
      defaultZone: http://eureka7001.com:7001/eureka/
# server:
# enable-self-preservation: false
spring:
  application:
    name: cloud-provider-hystrix-payment
# eviction-interval-timer-in-ms: 2000

2.1.3 Main startup class and business class

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

@RestController
@Slf4j
public class PaymentController {
    

    @Resource
    private PaymentService paymentService;

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

    @GetMapping("/payment/hystrix/ok/{id}")
    public String paymentInfo_OK(@PathVariable("id") Integer id){
    
        String result = paymentService.paymentInfo_OK(id);
        log.info("*******result:"+result);
        return result;
    }
    @GetMapping("/payment/hystrix/timeout/{id}")
    public String paymentInfo_TimeOut(@PathVariable("id") Integer id){
    
        String result = paymentService.paymentInfo_TimeOut(id);
        log.info("*******result:"+result);
        return result;
    }
}

@Service
public class PaymentService {
    

    // success 
    public String paymentInfo_OK(Integer id){
    
        return " Thread pool ："+Thread.currentThread().getName()+" paymentInfo_OK,id： "+id+"\t"+" Ha ha ha "  ;
    }

    // Failure 
    public String paymentInfo_TimeOut(Integer id){
    
        int timeNumber = 3;
        try {
     TimeUnit.SECONDS.sleep(timeNumber); }catch (Exception e) {
    e.printStackTrace();}
        return " Thread pool ："+Thread.currentThread().getName()+" paymentInfo_TimeOut,id： "+id+"\t"+" Purring "+"  Time consuming ( second )"+timeNumber;
    }
}

2.1.4 Normal test

start-up eureka7001, start-up cloud-provider-hystrix-payment8001

visit ：http://localhost:8001/payment/hystrix/ok/31 and http://localhost:8001/payment/hystrix/timeout/31

2.1.5 High concurrency testing

Turn on Jmeter, Come on 30000 A concurrent crush 8001,30000 All requests to visit paymentInfo_TimeOut service

result ：ok and timeout Both of these interfaces are going round and round

why? Pressure measurement only timeout Interface ,ok Why does the interface slow down ？

tomcat The default number of worker threads for is full , There are no extra threads to break down the stress and process .

2.2.cloud-consumer-feign-hystrix-order80

2.2.1 Change pom

<dependencies>
        <!-- newly added hystrix-->
        <dependency>
            <groupId>org.springframework.cloud</groupId>
            <artifactId>spring-cloud-starter-netflix-hystrix</artifactId>
        </dependency>
        <dependency>
            <groupId>org.springframework.cloud</groupId>
            <artifactId>spring-cloud-starter-openfeign</artifactId>
        </dependency>
        <dependency>
            <groupId>org.springframework.cloud</groupId>
            <artifactId>spring-cloud-starter-netflix-eureka-client</artifactId>
        </dependency>
        <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-starter-web</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>

2.2.2 Change yml

server
  port: 80

eureka:
  client:
    register-with-eureka: true    # I don't register myself with the registry 
    fetch-registry: true   # Say you're the registry , The responsibility is to maintain service instances , There's no need to retrieve Services 
    service-url:
             defaultZone: http://eureka7001.com:7001/eureka/

spring:
  application:
    name: cloud-provider-hystrix-order 

2.2.3 Main startup class and business class

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

@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);
}

@RestController
@Slf4j
public class OrderHystrixController {
    

    @Resource
    private PaymentHystrixService paymentHystrixService;

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

    @GetMapping("/consumer/payment/hystrix/ok/{id}")
    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);
        log.info("*******result:"+result);
        return result;
    }

2.2.4 test

http://localhost/consumer/payment/hystrix/ok/31 and http://localhost/consumer/payment/hystrix/timeout/31

2. 3 service degradation

Service degradation can be done on the server side , It can also be done on the client side .

2.3.1 Server side 8001 service degradation

The main boot class is annotated ：@EnableHystrix, The specific method is to add @HystrixCommand

Set the peak value of self call timeout , It can run normally during peak period , It's beyond the need to have a way to deal with it , For service degradation fallback

Once the call to the service method fails and an error message is thrown , Automatically called @HystrixCommand Marked fallbackMethod Call the specified method in the class

@Service
public class PaymentService {
    

    // success 
    public String paymentInfo_OK(Integer id){
    
        return " Thread pool ："+Thread.currentThread().getName()+" paymentInfo_OK,id： "+id+"\t"+" Ha ha ha "  ;
    }

    // Failure 
    @HystrixCommand(fallbackMethod = "paymentInfo_TimeOutHandler",commandProperties = {
    
            @HystrixProperty(name = "execution.isolation.thread.timeoutInMilliseconds",value = "3000")  //3 Within seconds is the normal business logic 
    })
    public String paymentInfo_TimeOut(Integer id){
    
       // int timeNumber = 5;
        int age = 10/0;
       // try { TimeUnit.SECONDS.sleep(timeNumber); }catch (Exception e) {e.printStackTrace();}
        //return " Thread pool ："+Thread.currentThread().getName()+" paymentInfo_TimeOut,id： "+id+"\t"+" Purring "+"  Time consuming ( second )"+timeNumber;
        return " Thread pool ："+Thread.currentThread().getName()+" paymentInfo_TimeOut,id： "+id+"\t"+" Purring "+"  Time consuming ( second )";
    }

    // How to cover the bottom 
    public String paymentInfo_TimeOutHandler(Integer id){
    
        return " Thread pool ："+Thread.currentThread().getName()+"  The system is busy ,  Please try again later  ,id： "+id+"\t"+" Cried wow ";
    }

}

2.3.2 client 80 service degradation

80 Order micro service , You can also protect yourself better , I also draw gourds to protect the client from degradation

feign:
  hystrix:
    enabled: true # If you deal with your own fault tolerance, turn it on . The opening method is different from the production end 

The main boot class is annotated ：@EnableHystrix, The specific method is to add @HystrixCommand

The current problem ： Mixed with business logic ？？？ confusion

according to cloud-consumer-feign-hystrix-order80 Already exist PaymentHystrixService Interface , Create a new class （PaymentFallbackService） Implement the interface , Uniformly handle exceptions for the methods in the interface

@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 , (┬＿┬)";
    }
}

stay PaymentHystrixService Indicate in fallback The class of is PaymentFallbackService

@Component
@FeignClient(value = "CLOUD-PROVIDER-HYSTRIX-PAYMENT",fallback = PaymentFallbackService.class)
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);

}

2.3.3 test

summary ：
When both the client and the server are configured with service degradation , It is normal for the server to set the timeout time on the client , Will follow the client's demotion logic . conversely , Then go through the server degradation logic .
If a runtime exception occurs on the server , Then the server degradation logic will be followed .
If the server goes down , The client demotion logic will be followed .