hystrix

 

测试时参数不能一样，否则无效，超时时间设置长点以免影响多线程测试
1，超时也走降级策略
2，maxQueueSize 最大排队长度。默认-1，使用SynchronousQueue。其他值则使用 LinkedBlockingQueue。如果要从-1换成其他值则需重启 设置该值即可实现多线程降级
2，若要动态调整，需要使用到下边这个配置hystrix.threadpool.default.queueSizeRejectionThreshold
排队线程数量阈值，默认为5，达到时拒绝，如果配置了该选项，队列的大小是该队列
3，调用线程允许请求HystrixCommand.GetFallback()的最大数量，默认10。超出时将会有异常抛出
4, command group 一般来说，可以是对应一个服务，多个command key对应这个服务的多个接口，多个接口的调用共享同一个线程池
5，也可以与Feign整合，来控制下游http调用


当整个微服务系统中，有一个节点出现异常情况，就有可能在高并发的情况下出现雪崩，导致调用它的上游系统出现响应延迟，响应延迟就会导致tomcat连接本耗尽，
导致该服务节点不能正常的接收到正常的情况，这就是服务雪崩行为
不要出现强制依赖，设置超时时间

@RequestMapping(value = "/myService")
@ResponseBody
@HystrixCommand(fallbackMethod = "getNameFallback", commandProperties = {  @HystrixProperty(name = "execution.isolation.thread.timeoutInMilliseconds", value = "20000")
    }, threadPoolKey = "hystrixDemoThreadPool", threadPoolProperties = {
             @HystrixProperty(name = "coreSize", value = "2")
            ,@HystrixProperty(name = "maxQueueSize", value = "1")
            ,@HystrixProperty(name = "queueSizeRejectionThreshold", value = "1")
    })
或者
#feign.hystrix.enabled= true
hystrix.command.default.execution.isolation.thread.timeoutInMilliseconds: 20000
hystrix.threadpool.default.coreSize: 1
hystrix.threadpool.default.maximumSize: 1
hystrix.threadpool.default.maxQueueSize: 1

public TestReponse getNameFallback(TestRequest request){
 System.out.println("getNameFallback***************"+request);
 TestReponse res = new TestReponse();
 res.setName("back");
 return res;
}

@EnableHystrix @SpringBootApplication

<dependency>  可以不用，eureka等其他模块已经引入
	<groupId>com.netflix.hystrix</groupId>
	<artifactId>hystrix-core</artifactId>
	<version>1.5.12</version>
</dependency>
<dependency>
	<groupId>com.netflix.hystrix</groupId>
	<artifactId>hystrix-javanica</artifactId>
	<version>1.5.12</version>
</dependency>
https://www.baiyp.ren/Hystrix%E7%9A%84%E4%BD%9C%E7%94%A8.html https://blog.csdn.net/qq_39363204/article/details/123282062

　　

<dependency>
	<groupId>org.springframework.cloud</groupId>
	<artifactId>spring-cloud-starter-eureka</artifactId>
	<version>1.4.7.RELEASE</version>
	<exclusions>
		<exclusion>
			<groupId>org.springframework.cloud</groupId>
			<artifactId>spring-cloud-netflix-core</artifactId>
		</exclusion>
	</exclusions>
</dependency>
<dependency>
	<groupId>io.github.openfeign</groupId>
	<artifactId>feign-hystrix</artifactId>
	<version>9.7.0</version>
</dependency>
<dependency>
	<groupId>org.springframework.cloud</groupId>
	<artifactId>spring-cloud-netflix-core</artifactId>
	<version>1.3.1.RELEASE</version>
</dependency>
<dependency>
	<groupId>org.springframework.cloud</groupId>
	<artifactId>spring-cloud-commons</artifactId>
	<version>1.3.6.RELEASE</version>
</dependency>


@Configuration
public class FeignConfiguration {
    @Bean
    @Scope("prototype")
    public Feign.Builder feignBuilder() {
        return HystrixFeign.builder();
    }

    @Bean
    public MyFeignClientFallbackOne fb() {
        return new MyFeignClientFallbackOne();
    }

public class MyFeignClientFallbackOne  implements MyFeignClient {
    @Override
    public TestReponse myFeignTest(Map<String, Object> map) {
        TestReponse re = new TestReponse();
        re.setName("xxxxxx111");
        return re;
    }

@FeignClient(value="myClient",url="http://localhost:9093",fallback = MyFeignClientFallbackOne.class,configuration = FeignConfiguration.class)
public interface MyFeignClient {
    @RequestMapping(value="/myService",method = RequestMethod.GET)
    TestReponse myFeignTest(Map<String,Object> map);//


测试
    @RequestMapping(value = "/mTestHttp2")//,method = RequestMethod.GET
    @ResponseBody
    public TestReponse mTestHttp2(TestRequest request){
        Map<String,Object> params = new HashMap<>();
        params.put("name","mynme");
        params.put("age","myagess");
        TestReponse res =  client.myFeignTest(params);
        System.out.println(res);

 @RequestMapping(value = "/myService2")//,method = RequestMethod.GET
    @ResponseBody
    public TestReponse myService(@RequestBody TestRequest request){
        System.out.println(" server "+request);
        TestReponse res = new TestReponse();
        return res;
    }

feign.hystrix.enabled= true
hystrix.command.default.execution.isolation.thread.timeoutInMilliseconds: 15000
hystrix.threadpool.default.coreSize: 1
hystrix.threadpool.default.maximumSize: 1
hystrix.threadpool.default.maxQueueSize: 1


获取熔断信息精细化处理
    @Bean
    public MyFeignClientFallback fbf() {
        return new MyFeignClientFallback();
    }


@FeignClient(value="myClient",url="http://localhost:9093", fallbackFactory=MyFeignClientFallback.class,configuration = FeignConfiguration.class)
public interface MyFeignClient {

public class MyFeignClientFallback  implements FallbackFactory<MyFeignClient> {
    @Override
    public MyFeignClient create(Throwable throwable) {
        return new MyFeignClient() {
            @Override
            public TestReponse myFeignTest(Map<String, Object> map) {
                System.out.println("熔断信息:"+throwable.toString());
                System.out.println("熔断信息:"+throwable.getMessage());
                TestReponse re = new TestReponse();
                re.setName("1111111111");
                return re;
            }
            @Override
            public TestReponse myFeignTest2(String name, String age) {
                return null;
            }


<parent>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-parent</artifactId>
<version>1.5.3.RELEASE</version><!--1.3.7 2.0.0 2.0.4-->
<relativePath/>
</parent>
<dependency>
	<groupId>org.springframework.boot</groupId>
	<artifactId>spring-boot-starter-web</artifactId>
</dependency>


两个线程循环掉，一个线程会熔断掉

熔断信息:java.util.concurrent.RejectedExecutionException: Task java.util.concurrent.FutureTask@6dd0313 rejected from java.util.concurrent.ThreadPoolExecutor@36e19049[Running, pool size = 1, active threads = 1, queued tasks = 1, completed tasks = 1]
Thread-9thready:TestReponse{name='1111111111', age='null'}

hystrix.threadpool.default.coreSize: 2 则不会熔断掉

hystrix.command.default.execution.isolation.thread.timeoutInMilliseconds: 15000
hystrix.threadpool.default.coreSize: 40
hystrix.threadpool.default.maximumSize: 100
hystrix.threadpool.default.maxQueueSize: 100