Hystrix断路器的打开与关闭

 

断路器是否打开

在命令结果没有缓存命中的时候，Hystrix在执行命令前需要检查断路器是否为打开状态：

如果断路器是打开的，那么Hystrix不会执行命令，而是转接到fallback处理逻辑

如果断路器是关闭的，那么Hystrix调到第5步(线程池/请求队列/信号量是否占满)，检查是否有可用资源来执行命令

 

断路器开启：

1.整个链路达到一定的阈值，默认情况下，10秒内产生超过20次请求，则符合第一个条件

2.满足第一个条件的情况下，如果请求的错误百分比大于阈值，则会打开断路器，默认50%

 

public class OpenMain {

 

public static void main(String[] args) {

//10秒内有10次请求满足第一个条件

ConfigurationManager.getConfigInstance().setProperty(

"hystrix.command.default.circuitBreaker.requestVolumeThreshold",10);

for(int i=0;i<15;i++){

ErrorCommand c=new ErrorCommand();

String result=c.execute();

System.out.println(result);

System.out.println(c.isCircuitBreakerOpen());

}

}

static class ErrorCommand extends HystrixCommand<String>{

public ErrorCommand(){

super(Setter.withGroupKey(HystrixCommandGroupKey.Factory.asKey("ExampleGroup"))

.andCommandPropertiesDefaults(HystrixCommandProperties.Setter().withExecutionTimeoutInMilliseconds(500)));

}

protected String run() throws InterruptedException{

Thread.sleep(800);

return "success";

}

protected String getFallback(){

return "fallback";

}

}

}

public class CloseMain {

 

public static void main(String[] args) throws InterruptedException {

ConfigurationManager.getConfigInstance().setProperty(

"hystrix.command.default.circuitBreaker.requestVolumeThreshold",3);

boolean isTimeout=true;

for(int i=0;i<10;i++){

TestCommand c=new TestCommand(isTimeout);

c.execute();

System.out.println(c.isCircuitBreakerOpen());

HealthCounts hc=c.getMetrics().getHealthCounts();

System.out.println("健康信息:"+hc.getTotalRequests());

if(c.isCircuitBreakerOpen()){

isTimeout=false;

System.out.println("------------断路器打开了，等待休眠期结束");

Thread.sleep(6000);

}

}

}

static class TestCommand extends HystrixCommand<String>{

private boolean isTimeout;

public TestCommand(boolean isTimeout){

super(Setter.withGroupKey(HystrixCommandGroupKey.Factory.asKey("ExampleGroup"))

.andCommandPropertiesDefaults(HystrixCommandProperties.Setter().withExecutionTimeoutInMilliseconds(500)));

this.isTimeout=isTimeout;

}

protected String run() throws InterruptedException{

if(isTimeout){

Thread.sleep(800);

}else{

Thread.sleep(200);

}

return "";

}

protected String getFallback(){

return "fallback";

}

}

}