circuitBreaker.requestVolumeThreshold不像预期的那样工作

Question

我正在测试Spring断路器，我忽略了"circuitBreaker.requestVolumeThreshold“参数实际上是如何works...See我的例子的要点.

@HystrixCommand(
            fallbackMethod = "invokeMicroServiceFallback",
            commandProperties = {
                @HystrixProperty(name = "execution.isolation.thread.timeoutInMilliseconds",
                        value = "30000"),
                @HystrixProperty(name = "circuitBreaker.requestVolumeThreshold",
                        value = "2"),
                @HystrixProperty(name = "circuitBreaker.sleepWindowInMilliseconds",
                        value = "500"),
                @HystrixProperty(name = "metrics.rollingStats.timeInMilliseconds",
                        value = "180000")
            },
            threadPoolProperties = {
                @HystrixProperty(name = "coreSize", value = "30"),
                @HystrixProperty(name = "metrics.rollingStats.timeInMilliseconds",
                        value = "180000")
            })
    public void invokeMicroService() {
        final RestTemplate restTemplate = new RestTemplate();

        final ServiceInstance serviceInstance = loadBalancer.choose("personsService");
        if (serviceInstance != null) {
            System.out.println("Invoking instance at URL: "+serviceInstance.getUri());
            System.out.println("Result :"+
                    restTemplate.getForObject(serviceInstance.getUri()+"/persons",
                            String.class));
        } else {
            System.out.println("Service is down...");
            throw new IllegalStateException("PersonsService is not running!");
        }
    }

    public void invokeMicroServiceFallback() {
        System.out.println("Waiting for circuit-breaker to close again...");
    }

如果我关闭personsService并在循环中调用invokeMicroService，那么我得到了很多输出，比如：

第一：

  Invoking instance at URL: <URL at my service>;
  "Waiting for circuit-breaker to close again..."

过了一段时间后，我又重复了一遍：

  Service is down...
  "Waiting for circuit-breaker to close again..."

circuitBreaker.requestVolumeThreshold在这里到底做了什么？为什么我不止两次尝试访问personsService？

提前谢谢..。

Answer 1

来自wiki https://github.com/Netflix/Hystrix/wiki/Configuration#circuitBreaker.requestVolumeThreshold

circuitBreaker.requestVolumeThreshold 此属性在滚动窗口中设置将触发电路的最小请求数。 例如，如果值为20，那么如果在滚动窗口(例如10秒的窗口)中只接收到19个请求，即使所有19个都失败了，电路也不会打开。