SpringCloud Hystrix

服务调用链路长，容易出现雪崩效应

Hystrix保证一个服务出错时，不会导致服务整体奔溃

hystrix中的重要概念:

1,服务降级，立即返回备用方案结果

比如当某个服务繁忙,不能让客户端的请求一直等待,应该立刻返回给客户端一个备选方案。立即返回

 @HystrixCommand(fallbackMethod = "paymentInfo_TimeOutHandler"

2,服务熔断，先关掉，又恢复调用

当某个服务出现问题,卡死了,不能让用户一直等待,需要关闭所有对此服务的访问

然后调用服务降级

3,服务限流

限流,比如秒杀场景,不能访问用户瞬间都访问服务器,限制一次只可以有多少请求

Service
public class PaymentService
{
    /**
     * 正常访问，肯定OK
     * @param id
     * @return
     */
    public String paymentInfo_OK(Integer id)
    {
        return "线程池:  "+Thread.currentThread().getName()+"  paymentInfo_OK,id:  "+id+"\t"+"O(∩_∩)O哈哈~";
    }

    @HystrixCommand(fallbackMethod = "paymentInfo_TimeOutHandler",commandProperties = {
            @HystrixProperty(name="execution.isolation.thread.timeoutInMilliseconds",value="5000")
    })
    public String paymentInfo_TimeOut(Integer id)
    {
        //int age = 10/0;
        try { TimeUnit.MILLISECONDS.sleep(3000); } catch (InterruptedException e) { e.printStackTrace(); }
        return "线程池:  "+Thread.currentThread().getName()+" id:  "+id+"\t"+"O(∩_∩)O哈哈~"+"  耗时(秒): ";
    }
    public String paymentInfo_TimeOutHandler(Integer id)
    {
        return "线程池:  "+Thread.currentThread().getName()+"  8001系统繁忙或者运行报错，请稍后再试,id:  "+id+"\t"+"o(╥﹏╥)o";
    }

    //=====服务熔断
    @HystrixCommand(fallbackMethod = "paymentCircuitBreaker_fallback",commandProperties = {
            @HystrixProperty(name = "circuitBreaker.enabled",value = "true"),// 是否开启断路器
            @HystrixProperty(name = "circuitBreaker.requestVolumeThreshold",value = "10"),// 请求次数
            @HystrixProperty(name = "circuitBreaker.sleepWindowInMilliseconds",value = "10000"), // 时间窗口期
            @HystrixProperty(name = "circuitBreaker.errorThresholdPercentage",value = "60"),// 失败率达到多少后跳闸
    })
    public String paymentCircuitBreaker(@PathVariable("id") Integer id)
    {
        if(id < 0)
        {
            throw new RuntimeException("******id 不能负数");
        }
        String serialNumber = IdUtil.simpleUUID();

        return Thread.currentThread().getName()+"\t"+"调用成功，流水号: " + serialNumber;
    }
    public String paymentCircuitBreaker_fallback(@PathVariable("id") Integer id)
    {
        return "id 不能负数，请稍后再试，/(ㄒoㄒ)/~~   id: " +id;
    }

fallbackMethod = "paymentInfo_TimeOutHandler"  　　//服务降级方法



服务熔断

    //=====服务熔断
    @HystrixCommand(fallbackMethod = "paymentCircuitBreaker_fallback",commandProperties = {
            @HystrixProperty(name = "circuitBreaker.enabled",value = "true"),// 是否开启断路器
            @HystrixProperty(name = "circuitBreaker.requestVolumeThreshold",value = "10"),// 请求次数
            @HystrixProperty(name = "circuitBreaker.sleepWindowInMilliseconds",value = "10000"), // 时间窗口期
            @HystrixProperty(name = "circuitBreaker.errorThresholdPercentage",value = "60"),// 失败率达到多少后跳闸
    })
    public String paymentCircuitBreaker(@PathVariable("id") Integer id)
    {
        if(id < 0)
        {
            throw new RuntimeException("******id 不能负数");
        }
        String serialNumber = IdUtil.simpleUUID();

        return Thread.currentThread().getName()+"\t"+"调用成功，流水号: " + serialNumber;
    }