Hystrix断路器不开路

Question

我在我的spring boot应用程序中使用Hystrix实现断路器，我的代码如下所示：

@service
public class MyServiceHandler {

    @HystrixCommand(fallbackMethod="fallback")
    
    public String callService() {
       // if(remote service is not reachable
       // throw ServiceException
    }
    
    public String fallback() {
       // return default response
    }
}

// In application.properties, I have below properties defined:
hystrix.command.default.execution.isolation.thread.timeoutInMilliseconds=10000
hystrix.command.default.circuitBreaker.requestVolumeThreshold=3
hystrix.command.default.circuitBreaker.sleepWindowInMilliseconds=30000
hystrix.threadpool.default.coreSize=4
hystrix.threadpool.default.metrics.rollingStats.timeInMilliseconds=200000

我看到每次callservice()失败时都会调用fallback（）。但3次故障后电路不开。在3次失败之后，我原以为它会直接调用fallback()并跳过callservice()。但这并没有发生。有人能告诉我我在这里做错了什么吗？

谢谢,B Jagan

下面是实际代码。我用这个玩得更远了。当我在RegistrationHystrix.RegisterSeller（）方法中直接调用远程服务时，我看到电路在重复失败时按预期打开。但是，当我将远程服务调用包装在spring重试模板中时，它继续进入回退方法，但电路从未打开。

@Service
public class RegistrationHystrix {
    Logger logger = LoggerFactory.getLogger(RegistrationHystrix.class);
    private RestTemplate restTemplate;
    private RetryTemplate retryTemplate;

    public RegistrationHystrix(RestTemplate restTemplate) {
        this.restTemplate = restTemplate;
        retryTemplate = new RetryTemplate();
        FixedBackOffPolicy fixedBackOffPolicy = new FixedBackOffPolicy();
        fixedBackOffPolicy.setBackOffPeriod(1000l);
        retryTemplate.setBackOffPolicy(fixedBackOffPolicy);
        SimpleRetryPolicy retryPolicy = new SimpleRetryPolicy();
        retryPolicy.setMaxAttempts(3);
        retryTemplate.setRetryPolicy(retryPolicy);
    }

    @HystrixCommand(fallbackMethod = "fallbackForRegisterSeller", commandKey = "ordermanagement")
    public String registerSeller(SellerDto sellerDto)  throws Exception {
        String response = retryTemplate.execute(new RetryCallback<String, Exception>() {
                   @Override
                   public String doWithRetry(RetryContext context) {
                           logger.info(String.format("Retry count %d", context.getRetryCount()));
                          return restTemplate.postForObject("/addSeller", sellerDto, String.class);
                   }
       });
       return response;
    }

    public List<SellerDto> getSellersList() {
        return restTemplate.getForObject("/sellersList", List.class);
    }

    public String fallbackForRegisterSeller(SellerDto sellerDto, Throwable t) {
        logger.error("Inside fall back, cause - {}", t.toString());
        return "Inside fallback method. Some error occured while calling service for seller registration";
    }
}

下面是service类，它又调用上面的Hystrix包装的服务。这个类又由控制器调用。

@Service
public class RegistrationServiceImpl implements RegistrationService {

    Logger logger = LoggerFactory.getLogger(RegistrationServiceImpl.class);
    private RegistrationHystrix registrationHystrix;


    public RegistrationServiceImpl(RegistrationHystrix registrationHystrix) {
        this.registrationHystrix = registrationHystrix;
    }

    @Override
    public String registerSeller(SellerDto sellerDto)  throws Exception {
        long start = System.currentTimeMillis();
        String registerSeller = registrationHystrix.registerSeller(sellerDto);
        logger.info("add seller call returned in - {}", System.currentTimeMillis() - start);
        return registerSeller;

    }

所以，我正在试图理解为什么断路器在使用它与spring RetryTemplate一起时没有像预期的那样工作。

Answer 1

您应该在测试时使用Metrics.HealthSnapshot.IntervalinMilliseconds。我猜你是在默认的500毫秒内执行所有3个请求，因此电路没有打开。您可以缩短此间隔，也可以在3个请求之间放置睡眠。