springcloud 入门系列（六）Hystrix-属性配置

「爱情、让人受尽委屈。」 2024-04-17 05:34 47阅读 0赞

昨天我们介绍了如何使用hystrix,并且对其有了初步的认识，今天我们进一步来了解hystrix.

下面是对hystrx 的设计目标和原则的一些描述，摘自网络：

https://www.cnblogs.com/cjsblog/p/9391819.html，也是hystrix在github 上的wiki翻译：

Hystrix被设计的目标是：

1.  对通过第三方客户端库访问的依赖项（通常是通过网络）的延迟和故障进行保护和控制。
2.  在复杂的分布式系统中阻止级联故障。
3.  快速失败，快速恢复。
4.  回退，尽可能优雅地降级。
5.  启用近实时监控、警报和操作控制。

**Hystrix****设计原则是什么**

*  防止任何单个依赖项耗尽所有容器（如Tomcat）用户线程。
 *  甩掉包袱，快速失败而不是排队。
 *  在任何可行的地方提供回退，以保护用户不受失败的影响。
 *  使用隔离技术（如隔离板、泳道和断路器模式）来限制任何一个依赖项的影响。
 *  通过近实时的度量、监视和警报来优化发现时间。
 *  通过配置的低延迟传播来优化恢复时间。
 *  支持对Hystrix的大多数方面的动态属性更改，允许使用低延迟反馈循环进行实时操作修改。
 *  避免在整个依赖客户端执行中出现故障，而不仅仅是在网络流量中。

**Hystrix****是如何实现它的目标的**

1.  用一个HystrixCommand 或者 HystrixObservableCommand （这是命令模式的一个例子）包装所有的对外部系统（或者依赖）的调用，典型地它们在一个单独的线程中执行
2.  调用超时时间比你自己定义的阈值要长。有一个默认值，对于大多数的依赖项你是可以自定义超时时间的。
3.  为每个依赖项维护一个小的线程池(或信号量)；如果线程池满了，那么该依赖性将会立即拒绝请求，而不是排队。
4.  调用的结果有这么几种：成功、失败（客户端抛出异常）、超时、拒绝。
5.  在一段时间内，如果服务的错误百分比超过了一个阈值，就会触发一个断路器来停止对特定服务的所有请求，无论是手动的还是自动的。
6.  当请求失败、被拒绝、超时或短路时，执行回退逻辑。
7.  近实时监控指标和配置变化。

通过上面的介绍，我们知道hystrix 有多种方式来实现服务的隔离，可以通过线程和信号量来控制，默认是线程池隔离实现。下面我们来看下@HystrixCommand注解都有哪些属性，并且如何来设置属性值：

我们先看下他的源码：

/**
     * Copyright 2012 Netflix, Inc.
     *
     * Licensed under the Apache License, Version 2.0 (the "License");
     * you may not use this file except in compliance with the License.
     * You may obtain a copy of the License at
     *
     * http://www.apache.org/licenses/LICENSE-2.0
     *
     * Unless required by applicable law or agreed to in writing, software
     * distributed under the License is distributed on an "AS IS" BASIS,
     * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
     * See the License for the specific language governing permissions and
     * limitations under the License.
     */
    package com.netflix.hystrix.contrib.javanica.annotation;
    
    import java.lang.annotation.Documented;
    import java.lang.annotation.ElementType;
    import java.lang.annotation.Inherited;
    import java.lang.annotation.Retention;
    import java.lang.annotation.RetentionPolicy;
    import java.lang.annotation.Target;
    
    
    /**
     * This annotation used to specify some methods which should be processes as hystrix commands.
     */
    @Target({ElementType.METHOD})
    @Retention(RetentionPolicy.RUNTIME)
    @Inherited
    @Documented
    public @interface HystrixCommand {
    
        /**
         * The command group key is used for grouping together commands such as for reporting,
         * alerting, dashboards or team/library ownership.
         * <p/>
         * default => the runtime class name of annotated method
         *
         * @return group key
         */
        String groupKey() default "";
    
        /**
         * Hystrix command key.
         * <p/>
         * default => the name of annotated method. for example:
         * <code>
         *     ...
         *     @HystrixCommand
         *     public User getUserById(...)
         *     ...
         *     the command name will be: 'getUserById'
         * </code>
         *
         * @return command key
         */
        String commandKey() default "";
    
        /**
         * The thread-pool key is used to represent a
         * HystrixThreadPool for monitoring, metrics publishing, caching and other such uses.
         *
         * @return thread pool key
         */
        String threadPoolKey() default "";
    
        /**
         * Specifies a method to process fallback logic.
         * A fallback method should be defined in the same class where is HystrixCommand.
         * Also a fallback method should have same signature to a method which was invoked as hystrix command.
         * for example:
         * <code>
         *      @HystrixCommand(fallbackMethod = "getByIdFallback")
         *      public String getById(String id) {...}
         *
         *      private String getByIdFallback(String id) {...}
         * </code>
         * Also a fallback method can be annotated with {@link HystrixCommand}
         * <p/>
         * default => see {@link com.netflix.hystrix.contrib.javanica.command.GenericCommand#getFallback()}
         *
         * @return method name
         */
        String fallbackMethod() default "";
    
        /**
         * Specifies command properties.
         *
         * @return command properties
         */
        HystrixProperty[] commandProperties() default {};
    
        /**
         * Specifies thread pool properties.
         *
         * @return thread pool properties
         */
        HystrixProperty[] threadPoolProperties() default {};
    
        /**
         * Defines exceptions which should be ignored.
         * Optionally these can be wrapped in HystrixRuntimeException if raiseHystrixExceptions contains RUNTIME_EXCEPTION.
         *
         * @return exceptions to ignore
         */
        Class<? extends Throwable>[] ignoreExceptions() default {};
    
        /**
         * Specifies the mode that should be used to execute hystrix observable command.
         * For more information see {@link ObservableExecutionMode}.
         *
         * @return observable execution mode
         */
        ObservableExecutionMode observableExecutionMode() default ObservableExecutionMode.EAGER;
    
        /**
         * When includes RUNTIME_EXCEPTION, any exceptions that are not ignored are wrapped in HystrixRuntimeException.
         *
         * @return exceptions to wrap
         */
        HystrixException[] raiseHystrixExceptions() default {};
    
        /**
         * Specifies default fallback method for the command. If both {@link #fallbackMethod} and {@link #defaultFallback}
         * methods are specified then specific one is used.
         * note: default fallback method cannot have parameters, return type should be compatible with command return type.
         *
         * @return the name of default fallback method
         */
        String defaultFallback() default "";
    }

源码中对属性的意思已经做了详尽的注释，这里不再累述，下面我们就来做一些我们实际当中大概率需要用到的配置做实验，比如设定使用线程池隔离，设置线程池的参数，以及服务执行超时时间；

先看代码：

@HystrixCommand(commandKey = "hello",fallbackMethod = "fallback",threadPoolProperties = {
                @HystrixProperty(name = "coreSize",value = "2"), // 线程核心数目
                @HystrixProperty(name = "maxQueueSize",value="3") // 线程池队列大小
    
        },commandProperties = {
                @HystrixProperty(name = "execution.isolation.strategy",value = "THREAD"), // 使用线程池隔离
                @HystrixProperty(name = "execution.isolation.thread.timeoutInMilliseconds",value = "1000" ) // hystrix 超时时间
        }
        )
        public String hello(String name) throws InterruptedException {
            Stopwatch stopwatch = Stopwatch.createStarted();
            Random random = new Random();
            int r = random.nextInt(3000);
            Thread.sleep(r);
            log.info("服务耗时：{}",stopwatch.stop());
            return "hello world!" + name;
        }
    
        /**
         * 错误回调方法参数签名必须与原方法一致
         *
         * @param name
         * @return
         */
        public String fallback(String name, Throwable e) {
            log.info("这是造成服务降级的异常信息：{}",name, e);
            return "this is fallback message! ";
        }

我们设置服务启用线程池进行隔离，并且设置线程池大小为2，线程等待队列为3，以及超时时间1s。我们让服务线程随机睡眠3s内，来测试超时，我们启动服务并发送请求，查看控制台：

![https://mmbiz.qpic.cn/mmbiz\_png/StSSauj2rMria8AP4IXpMYxcHvJtKw84tE6L2MgTibibZFZ6bRVuchDEP52ibWEjU7jRrJAmUC1AuFAhRwHC2Zw7Xg/640?wx\_fmt=png][https_mmbiz.qpic.cn_mmbiz_png_StSSauj2rMria8AP4IXpMYxcHvJtKw84tE6L2MgTibibZFZ6bRVuchDEP52ibWEjU7jRrJAmUC1AuFAhRwHC2Zw7Xg_640_wx_fmt_png]

我们看到超时，fallback 方法被执行，并返回兜底数据。我们再修改线程睡眠时间来验证线程隔离。

同时我们再设置启动并发线程来调用接口来验证线程池配置的参数：

@RestController
    public class Controller {
    
        @Autowired
        private HelloServiceWithFallback helloServiceWithFallback;
    
        @GetMapping("test")
        public String test(Integer times) throws InterruptedException {
    
            for (int i = 0;i<times; i++){
                RunnAlble runnAlble = new RunnAlble();
                new Thread(runnAlble).start();
            }
            return helloServiceWithFallback.hello("ethan!!");
        }
    
        class RunnAlble implements Runnable{
    
            @Override
            public void run() {
                try {
                    helloServiceWithFallback.hello("ethan!!");
                } catch (InterruptedException e) {
                    e.printStackTrace();
                }
            }
        }
    
    }

我们设置请求参数time=4，也就是我们同时启动5个线程去执行服务，理论上可能会出现超时情况：

![https://mmbiz.qpic.cn/mmbiz\_png/StSSauj2rMria8AP4IXpMYxcHvJtKw84tqNk0J6926qbT4Pju0sD80EHRiaCJGs9880NtEkJqqhjItqRsI58micBQ/640?wx\_fmt=png][https_mmbiz.qpic.cn_mmbiz_png_StSSauj2rMria8AP4IXpMYxcHvJtKw84tqNk0J6926qbT4Pju0sD80EHRiaCJGs9880NtEkJqqhjItqRsI58micBQ_640_wx_fmt_png]

果然超时了，但是为什么会出现超时呢，因为我们的线程数目设置的是2，超过2个的请求会进入队列等待，所以就会出现超时情况。

下面我们设置times=5 也就是会生成6个线程去请求，我们看下测试结果：

![https://mmbiz.qpic.cn/mmbiz\_png/StSSauj2rMria8AP4IXpMYxcHvJtKw84t2giaCZB7mfn2qY4O3icuxMqSqlIKLkKQlIBgXR4kD7FOhNL5VCKUz2NA/640?wx\_fmt=png][https_mmbiz.qpic.cn_mmbiz_png_StSSauj2rMria8AP4IXpMYxcHvJtKw84t2giaCZB7mfn2qY4O3icuxMqSqlIKLkKQlIBgXR4kD7FOhNL5VCKUz2NA_640_wx_fmt_png]

看到后面的请求被拒绝执行了，请求数目大于（coreSize+maxQueueSize）数目就会直接拒绝请求返回fallback方法结果。

我们再来修改配置，测试断路器的属性配置；

@HystrixCommand(commandKey = "hello",fallbackMethod = "fallback",threadPoolProperties = {
                @HystrixProperty(name = "coreSize",value = "2"), // 线程核心数目
                @HystrixProperty(name = "maxQueueSize",value="3") // 线程池队列大小
    
        },commandProperties = {
                @HystrixProperty(name = "execution.isolation.strategy",value = "THREAD"), // 使用线程池隔离
                @HystrixProperty(name = "execution.isolation.thread.timeoutInMilliseconds",value = "1000" ) ,// hystrix 超时时间
                @HystrixProperty(name = "circuitBreaker.enabled",value = "true" ), //开启熔断器
                @HystrixProperty(name = "circuitBreaker.requestVolumeThreshold",value = "3" ) // 窗口时间内多少个请求失败了，会打开断路器
        }
        )
        public String hello(String name) throws InterruptedException {
            log.info("hello start!");
            Stopwatch stopwatch = Stopwatch.createStarted();
    //        Random random = new Random();
    //        int r = random.nextInt(5);
            Thread.sleep(1200);
            log.info("服务耗时：{}",stopwatch.stop());
            return "hello world!" + name;
        }
    
        /**
         * 错误回调方法参数签名必须与原方法一致
         *
         * @param name
         * @return
         */
        public String fallback(String name, Throwable e) {
            log.info("这是造成服务降级的异常信息：{}",name, e);
            return "this is fallback message! ";
        }

这次我们修改了线程睡眠时间，让其超时，新增参数：

开启短路器，并且设置窗口时间内5次请求失败则打开断路器，也就是说，只要窗口时间内5次请求都失败了，则后面直接进入fallback方法（该服务被熔断了），设置times=5，再看控制台日志输出：

2019-07-17 17:27:17.333  INFO 3532 --- \[nio-8888-exec-1\] o.a.c.c.C.\[Tomcat\].\[localhost\].\[/\]       : Initializing Spring DispatcherServlet 'dispatcherServlet'2019-07-17 17:27:17.333  INFO 3532 --- \[nio-8888-exec-1\] o.s.web.servlet.DispatcherServlet        : Initializing Servlet 'dispatcherServlet'2019-07-17 17:27:17.339  INFO 3532 --- \[nio-8888-exec-1\] o.s.web.servlet.DispatcherServlet        : Completed initialization in 6 ms2019-07-17 17:27:17.586  INFO 3532 --- \[      Thread-19\] c.e.hystrix.HelloServiceWithFallback     : 这是造成服务降级的异常信息：ethan!!java.util.concurrent.RejectedExecutionException: Task java.util.concurrent.FutureTask@cab906f rejected from java.util.concurrent.ThreadPoolExecutor@206f407\[Running, pool size = 1, active threads = 1, queued tasks = 3, completed tasks = 0\]  at java.util.concurrent.ThreadPoolExecutor$AbortPolicy.rejectedExecution(ThreadPoolExecutor.java:2047) ~\[na:1.8.0\_131\]  at java.util.concurrent.ThreadPoolExecutor.reject(ThreadPoolExecutor.java:823) ~\[na:1.8.0\_131\]  at java.util.concurrent.ThreadPoolExecutor.execute(ThreadPoolExecutor.java:1369) ~\[na:1.8.0\_131\]  at java.util.concurrent.AbstractExecutorService.submit(AbstractExecutorService.java:112) ~\[na:1.8.0\_131\]  at com.netflix.hystrix.strategy.concurrency.HystrixContextScheduler$ThreadPoolWorker.schedule(HystrixContextScheduler.java:172) ~\[hystrix-core-1.5.18.jar:1.5.18\]  at com.netflix.hystrix.strategy.concurrency.HystrixContextScheduler$HystrixContextSchedulerWorker.schedule(HystrixContextScheduler.java:106) ~\[hystrix-core-1.5.18.jar:1.5.18\]  at rx.internal.operators.OperatorSubscribeOn.call(OperatorSubscribeOn.java:50) ~\[rxjava-1.3.8.jar:1.3.8\]  at rx.internal.operators.OperatorSubscribeOn.call(OperatorSubscribeOn.java:30) ~\[rxjava-1.3.8.jar:1.3.8\]  at rx.internal.operators.OnSubscribeLift.call(OnSubscribeLift.java:48) ~\[rxjava-1.3.8.jar:1.3.8\]  at rx.internal.operators.OnSubscribeLift.call(OnSubscribeLift.java:30) ~\[rxjava-1.3.8.jar:1.3.8\]  at rx.Observable.unsafeSubscribe(Observable.java:10327) \[rxjava-1.3.8.jar:1.3.8\]  at rx.internal.operators.OnSubscribeDoOnEach.call(OnSubscribeDoOnEach.java:41) \[rxjava-1.3.8.jar:1.3.8\]  at rx.internal.operators.OnSubscribeDoOnEach.call(OnSubscribeDoOnEach.java:30) \[rxjava-1.3.8.jar:1.3.8\]  at rx.Observable.unsafeSubscribe(Observable.java:10327) \[rxjava-1.3.8.jar:1.3.8\]  at rx.internal.operators.OnSubscribeDoOnEach.call(OnSubscribeDoOnEach.java:41) \[rxjava-1.3.8.jar:1.3.8\]  at rx.internal.operators.OnSubscribeDoOnEach.call(OnSubscribeDoOnEach.java:30) \[rxjava-1.3.8.jar:1.3.8\]  at rx.internal.operators.OnSubscribeLift.call(OnSubscribeLift.java:48) ~\[rxjava-1.3.8.jar:1.3.8\]  at rx.internal.operators.OnSubscribeLift.call(OnSubscribeLift.java:30) ~\[rxjava-1.3.8.jar:1.3.8\]  at rx.Observable.unsafeSubscribe(Observable.java:10327) \[rxjava-1.3.8.jar:1.3.8\]  at rx.internal.operators.OnSubscribeDoOnEach.call(OnSubscribeDoOnEach.java:41) \[rxjava-1.3.8.jar:1.3.8\]  at rx.internal.operators.OnSubscribeDoOnEach.call(OnSubscribeDoOnEach.java:30) \[rxjava-1.3.8.jar:1.3.8\]  at rx.Observable.unsafeSubscribe(Observable.java:10327) \[rxjava-1.3.8.jar:1.3.8\]  at rx.internal.operators.OnSubscribeDoOnEach.call(OnSubscribeDoOnEach.java:41) \[rxjava-1.3.8.jar:1.3.8\]  at rx.internal.operators.OnSubscribeDoOnEach.call(OnSubscribeDoOnEach.java:30) \[rxjava-1.3.8.jar:1.3.8\]  at rx.Observable.unsafeSubscribe(Observable.java:10327) \[rxjava-1.3.8.jar:1.3.8\]  at rx.internal.operators.OnSubscribeDoOnEach.call(OnSubscribeDoOnEach.java:41) \[rxjava-1.3.8.jar:1.3.8\]  at rx.internal.operators.OnSubscribeDoOnEach.call(OnSubscribeDoOnEach.java:30) \[rxjava-1.3.8.jar:1.3.8\]  at rx.internal.operators.OnSubscribeLift.call(OnSubscribeLift.java:48) ~\[rxjava-1.3.8.jar:1.3.8\]  at rx.internal.operators.OnSubscribeLift.call(OnSubscribeLift.java:30) ~\[rxjava-1.3.8.jar:1.3.8\]  at rx.Observable.unsafeSubscribe(Observable.java:10327) \[rxjava-1.3.8.jar:1.3.8\]  at rx.internal.operators.OnSubscribeDefer.call(OnSubscribeDefer.java:51) \[rxjava-1.3.8.jar:1.3.8\]  at rx.internal.operators.OnSubscribeDefer.call(OnSubscribeDefer.java:35) \[rxjava-1.3.8.jar:1.3.8\]  at rx.Observable.unsafeSubscribe(Observable.java:10327) \[rxjava-1.3.8.jar:1.3.8\]  at rx.internal.operators.OnSubscribeMap.call(OnSubscribeMap.java:48) \[rxjava-1.3.8.jar:1.3.8\]  at rx.internal.operators.OnSubscribeMap.call(OnSubscribeMap.java:33) \[rxjava-1.3.8.jar:1.3.8\]  at rx.Observable.unsafeSubscribe(Observable.java:10327) \[rxjava-1.3.8.jar:1.3.8\]  at rx.internal.operators.OnSubscribeDoOnEach.call(OnSubscribeDoOnEach.java:41) \[rxjava-1.3.8.jar:1.3.8\]  at rx.internal.operators.OnSubscribeDoOnEach.call(OnSubscribeDoOnEach.java:30) \[rxjava-1.3.8.jar:1.3.8\]  at rx.internal.operators.OnSubscribeLift.call(OnSubscribeLift.java:48) ~\[rxjava-1.3.8.jar:1.3.8\]  at rx.internal.operators.OnSubscribeLift.call(OnSubscribeLift.java:30) ~\[rxjava-1.3.8.jar:1.3.8\]  at rx.Observable.unsafeSubscribe(Observable.java:10327) \[rxjava-1.3.8.jar:1.3.8\]  at rx.internal.operators.OnSubscribeDoOnEach.call(OnSubscribeDoOnEach.java:41) \[rxjava-1.3.8.jar:1.3.8\]  at rx.internal.operators.OnSubscribeDoOnEach.call(OnSubscribeDoOnEach.java:30) \[rxjava-1.3.8.jar:1.3.8\]  at rx.Observable.unsafeSubscribe(Observable.java:10327) \[rxjava-1.3.8.jar:1.3.8\]  at rx.internal.operators.OnSubscribeDefer.call(OnSubscribeDefer.java:51) \[rxjava-1.3.8.jar:1.3.8\]  at rx.internal.operators.OnSubscribeDefer.call(OnSubscribeDefer.java:35) \[rxjava-1.3.8.jar:1.3.8\]  at rx.internal.operators.OnSubscribeLift.call(OnSubscribeLift.java:48) ~\[rxjava-1.3.8.jar:1.3.8\]  at rx.internal.operators.OnSubscribeLift.call(OnSubscribeLift.java:30) ~\[rxjava-1.3.8.jar:1.3.8\]  at rx.Observable.subscribe(Observable.java:10423) \[rxjava-1.3.8.jar:1.3.8\]  at rx.Observable.subscribe(Observable.java:10390) \[rxjava-1.3.8.jar:1.3.8\]  at rx.internal.operators.BlockingOperatorToFuture.toFuture(BlockingOperatorToFuture.java:51) \[rxjava-1.3.8.jar:1.3.8\]  at rx.observables.BlockingObservable.toFuture(BlockingObservable.java:410) \[rxjava-1.3.8.jar:1.3.8\]  at com.netflix.hystrix.HystrixCommand.queue(HystrixCommand.java:378) \[hystrix-core-1.5.18.jar:1.5.18\]  at com.netflix.hystrix.HystrixCommand.execute(HystrixCommand.java:344) \[hystrix-core-1.5.18.jar:1.5.18\]  at com.netflix.hystrix.contrib.javanica.command.CommandExecutor.execute(CommandExecutor.java:52) \[hystrix-javanica-1.5.18.jar:1.5.18\]  at com.netflix.hystrix.contrib.javanica.aop.aspectj.HystrixCommandAspect.methodsAnnotatedWithHystrixCommand(HystrixCommandAspect.java:101) \[hystrix-javanica-1.5.18.jar:1.5.18\]  at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) ~\[na:1.8.0\_131\]  at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62) ~\[na:1.8.0\_131\]  at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43) ~\[na:1.8.0\_131\]  at java.lang.reflect.Method.invoke(Method.java:498) ~\[na:1.8.0\_131\]  at org.springframework.aop.aspectj.AbstractAspectJAdvice.invokeAdviceMethodWithGivenArgs(AbstractAspectJAdvice.java:644) \[spring-aop-5.1.8.RELEASE.jar:5.1.8.RELEASE\]  at org.springframework.aop.aspectj.AbstractAspectJAdvice.invokeAdviceMethod(AbstractAspectJAdvice.java:633) \[spring-aop-5.1.8.RELEASE.jar:5.1.8.RELEASE\]  at org.springframework.aop.aspectj.AspectJAroundAdvice.invoke(AspectJAroundAdvice.java:70) \[spring-aop-5.1.8.RELEASE.jar:5.1.8.RELEASE\]  at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:175) \[spring-aop-5.1.8.RELEASE.jar:5.1.8.RELEASE\]  at org.springframework.aop.interceptor.ExposeInvocationInterceptor.invoke(ExposeInvocationInterceptor.java:93) \[spring-aop-5.1.8.RELEASE.jar:5.1.8.RELEASE\]  at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:186) \[spring-aop-5.1.8.RELEASE.jar:5.1.8.RELEASE\]  at org.springframework.aop.framework.CglibAopProxy$DynamicAdvisedInterceptor.intercept(CglibAopProxy.java:688) \[spring-aop-5.1.8.RELEASE.jar:5.1.8.RELEASE\]  at com.example.hystrix.HelloServiceWithFallback$$EnhancerBySpringCGLIB$$680f4c58.hello(<generated>) \[classes/:na\]  at com.example.hystrix.Controller$RunnAlble.run(Controller.java:32) \[classes/:na\]  at java.lang.Thread.run(Thread.java:748) \[na:1.8.0\_131\]2019-07-17 17:27:17.587  INFO 3532 --- \[eWithFallback-2\] c.e.hystrix.HelloServiceWithFallback     : hello start!2019-07-17 17:27:17.587  INFO 3532 --- \[eWithFallback-1\] c.e.hystrix.HelloServiceWithFallback     : hello start!2019-07-17 17:27:18.576  INFO 3532 --- \[ HystrixTimer-4\] c.e.hystrix.HelloServiceWithFallback     : 这是造成服务降级的异常信息：ethan!!com.netflix.hystrix.exception.HystrixTimeoutException: null  at com.netflix.hystrix.AbstractCommand$HystrixObservableTimeoutOperator$1.run(AbstractCommand.java:1142) ~\[hystrix-core-1.5.18.jar:1.5.18\]  at com.netflix.hystrix.strategy.concurrency.HystrixContextRunnable$1.call(HystrixContextRunnable.java:41) ~\[hystrix-core-1.5.18.jar:1.5.18\]  at com.netflix.hystrix.strategy.concurrency.HystrixContextRunnable$1.call(HystrixContextRunnable.java:37) ~\[hystrix-core-1.5.18.jar:1.5.18\]  at com.netflix.hystrix.strategy.concurrency.HystrixContextRunnable.run(HystrixContextRunnable.java:57) ~\[hystrix-core-1.5.18.jar:1.5.18\]  at com.netflix.hystrix.AbstractCommand$HystrixObservableTimeoutOperator$2.tick(AbstractCommand.java:1159) \[hystrix-core-1.5.18.jar:1.5.18\]  at com.netflix.hystrix.util.HystrixTimer$1.run(HystrixTimer.java:99) \[hystrix-core-1.5.18.jar:1.5.18\]  at java.util.concurrent.Executors$RunnableAdapter.call(Executors.java:511) \[na:1.8.0\_131\]  at java.util.concurrent.FutureTask.runAndReset$$$capture(FutureTask.java:308) \[na:1.8.0\_131\]  at java.util.concurrent.FutureTask.runAndReset(FutureTask.java) \[na:1.8.0\_131\]  at java.util.concurrent.ScheduledThreadPoolExecutor$ScheduledFutureTask.access$301(ScheduledThreadPoolExecutor.java:180) \[na:1.8.0\_131\]  at java.util.concurrent.ScheduledThreadPoolExecutor$ScheduledFutureTask.run(ScheduledThreadPoolExecutor.java:294) \[na:1.8.0\_131\]  at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1142) \[na:1.8.0\_131\]  at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:617) \[na:1.8.0\_131\]  at java.lang.Thread.run(Thread.java:748) \[na:1.8.0\_131\]2019-07-17 17:27:18.577  INFO 3532 --- \[eWithFallback-1\] c.e.hystrix.HelloServiceWithFallback     : hello start!2019-07-17 17:27:18.577  INFO 3532 --- \[ HystrixTimer-2\] c.e.hystrix.HelloServiceWithFallback     : 这是造成服务降级的异常信息：ethan!!com.netflix.hystrix.exception.HystrixTimeoutException: null  at com.netflix.hystrix.AbstractCommand$HystrixObservableTimeoutOperator$1.run(AbstractCommand.java:1142) ~\[hystrix-core-1.5.18.jar:1.5.18\]  at com.netflix.hystrix.strategy.concurrency.HystrixContextRunnable$1.call(HystrixContextRunnable.java:41) ~\[hystrix-core-1.5.18.jar:1.5.18\]  at com.netflix.hystrix.strategy.concurrency.HystrixContextRunnable$1.call(HystrixContextRunnable.java:37) ~\[hystrix-core-1.5.18.jar:1.5.18\]  at com.netflix.hystrix.strategy.concurrency.HystrixContextRunnable.run(HystrixContextRunnable.java:57) ~\[hystrix-core-1.5.18.jar:1.5.18\]  at com.netflix.hystrix.AbstractCommand$HystrixObservableTimeoutOperator$2.tick(AbstractCommand.java:1159) \[hystrix-core-1.5.18.jar:1.5.18\]  at com.netflix.hystrix.util.HystrixTimer$1.run(HystrixTimer.java:99) \[hystrix-core-1.5.18.jar:1.5.18\]  at java.util.concurrent.Executors$RunnableAdapter.call(Executors.java:511) \[na:1.8.0\_131\]  at java.util.concurrent.FutureTask.runAndReset$$$capture(FutureTask.java:308) \[na:1.8.0\_131\]  at java.util.concurrent.FutureTask.runAndReset(FutureTask.java) \[na:1.8.0\_131\]  at java.util.concurrent.ScheduledThreadPoolExecutor$ScheduledFutureTask.access$301(ScheduledThreadPoolExecutor.java:180) \[na:1.8.0\_131\]  at java.util.concurrent.ScheduledThreadPoolExecutor$ScheduledFutureTask.run(ScheduledThreadPoolExecutor.java:294) \[na:1.8.0\_131\]  at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1142) \[na:1.8.0\_131\]  at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:617) \[na:1.8.0\_131\]  at java.lang.Thread.run(Thread.java:748) \[na:1.8.0\_131\]2019-07-17 17:27:18.579  INFO 3532 --- \[ HystrixTimer-1\] c.e.hystrix.HelloServiceWithFallback     : 这是造成服务降级的异常信息：ethan!!com.netflix.hystrix.exception.HystrixTimeoutException: null  at com.netflix.hystrix.AbstractCommand$HystrixObservableTimeoutOperator$1.run(AbstractCommand.java:1142) ~\[hystrix-core-1.5.18.jar:1.5.18\]  at com.netflix.hystrix.strategy.concurrency.HystrixContextRunnable$1.call(HystrixContextRunnable.java:41) ~\[hystrix-core-1.5.18.jar:1.5.18\]  at com.netflix.hystrix.strategy.concurrency.HystrixContextRunnable$1.call(HystrixContextRunnable.java:37) ~\[hystrix-core-1.5.18.jar:1.5.18\]  at com.netflix.hystrix.strategy.concurrency.HystrixContextRunnable.run(HystrixContextRunnable.java:57) ~\[hystrix-core-1.5.18.jar:1.5.18\]  at com.netflix.hystrix.AbstractCommand$HystrixObservableTimeoutOperator$2.tick(AbstractCommand.java:1159) \[hystrix-core-1.5.18.jar:1.5.18\]  at com.netflix.hystrix.util.HystrixTimer$1.run(HystrixTimer.java:99) \[hystrix-core-1.5.18.jar:1.5.18\]  at java.util.concurrent.Executors$RunnableAdapter.call(Executors.java:511) \[na:1.8.0\_131\]  at java.util.concurrent.FutureTask.runAndReset$$$capture(FutureTask.java:308) \[na:1.8.0\_131\]  at java.util.concurrent.FutureTask.runAndReset(FutureTask.java) \[na:1.8.0\_131\]  at java.util.concurrent.ScheduledThreadPoolExecutor$ScheduledFutureTask.access$301(ScheduledThreadPoolExecutor.java:180) \[na:1.8.0\_131\]  at java.util.concurrent.ScheduledThreadPoolExecutor$ScheduledFutureTask.run(ScheduledThreadPoolExecutor.java:294) \[na:1.8.0\_131\]  at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1142) \[na:1.8.0\_131\]  at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:617) \[na:1.8.0\_131\]  at java.lang.Thread.run(Thread.java:748) \[na:1.8.0\_131\]2019-07-17 17:27:18.579  INFO 3532 --- \[ HystrixTimer-3\] c.e.hystrix.HelloServiceWithFallback     : 这是造成服务降级的异常信息：ethan!!com.netflix.hystrix.exception.HystrixTimeoutException: null  at com.netflix.hystrix.AbstractCommand$HystrixObservableTimeoutOperator$1.run(AbstractCommand.java:1142) ~\[hystrix-core-1.5.18.jar:1.5.18\]  at com.netflix.hystrix.strategy.concurrency.HystrixContextRunnable$1.call(HystrixContextRunnable.java:41) ~\[hystrix-core-1.5.18.jar:1.5.18\]  at com.netflix.hystrix.strategy.concurrency.HystrixContextRunnable$1.call(HystrixContextRunnable.java:37) ~\[hystrix-core-1.5.18.jar:1.5.18\]  at com.netflix.hystrix.strategy.concurrency.HystrixContextRunnable.run(HystrixContextRunnable.java:57) ~\[hystrix-core-1.5.18.jar:1.5.18\]  at com.netflix.hystrix.AbstractCommand$HystrixObservableTimeoutOperator$2.tick(AbstractCommand.java:1159) \[hystrix-core-1.5.18.jar:1.5.18\]  at com.netflix.hystrix.util.HystrixTimer$1.run(HystrixTimer.java:99) \[hystrix-core-1.5.18.jar:1.5.18\]  at java.util.concurrent.Executors$RunnableAdapter.call(Executors.java:511) \[na:1.8.0\_131\]  at java.util.concurrent.FutureTask.runAndReset$$$capture(FutureTask.java:308) \[na:1.8.0\_131\]  at java.util.concurrent.FutureTask.runAndReset(FutureTask.java) \[na:1.8.0\_131\]  at java.util.concurrent.ScheduledThreadPoolExecutor$ScheduledFutureTask.access$301(ScheduledThreadPoolExecutor.java:180) \[na:1.8.0\_131\]  at java.util.concurrent.ScheduledThreadPoolExecutor$ScheduledFutureTask.run(ScheduledThreadPoolExecutor.java:294) \[na:1.8.0\_131\]  at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1142) \[na:1.8.0\_131\]  at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:617) \[na:1.8.0\_131\]  at java.lang.Thread.run(Thread.java:748) \[na:1.8.0\_131\]2019-07-17 17:27:18.580  INFO 3532 --- \[ HystrixTimer-4\] c.e.hystrix.HelloServiceWithFallback     : 这是造成服务降级的异常信息：ethan!!com.netflix.hystrix.exception.HystrixTimeoutException: null  at com.netflix.hystrix.AbstractCommand$HystrixObservableTimeoutOperator$1.run(AbstractCommand.java:1142) ~\[hystrix-core-1.5.18.jar:1.5.18\]  at com.netflix.hystrix.strategy.concurrency.HystrixContextRunnable$1.call(HystrixContextRunnable.java:41) ~\[hystrix-core-1.5.18.jar:1.5.18\]  at com.netflix.hystrix.strategy.concurrency.HystrixContextRunnable$1.call(HystrixContextRunnable.java:37) ~\[hystrix-core-1.5.18.jar:1.5.18\]  at com.netflix.hystrix.strategy.concurrency.HystrixContextRunnable.run(HystrixContextRunnable.java:57) ~\[hystrix-core-1.5.18.jar:1.5.18\]  at com.netflix.hystrix.AbstractCommand$HystrixObservableTimeoutOperator$2.tick(AbstractCommand.java:1159) \[hystrix-core-1.5.18.jar:1.5.18\]  at com.netflix.hystrix.util.HystrixTimer$1.run(HystrixTimer.java:99) \[hystrix-core-1.5.18.jar:1.5.18\]  at java.util.concurrent.Executors$RunnableAdapter.call(Executors.java:511) \[na:1.8.0\_131\]  at java.util.concurrent.FutureTask.runAndReset$$$capture(FutureTask.java:308) \[na:1.8.0\_131\]  at java.util.concurrent.FutureTask.runAndReset(FutureTask.java) \[na:1.8.0\_131\]  at java.util.concurrent.ScheduledThreadPoolExecutor$ScheduledFutureTask.access$301(ScheduledThreadPoolExecutor.java:180) \[na:1.8.0\_131\]  at java.util.concurrent.ScheduledThreadPoolExecutor$ScheduledFutureTask.run(ScheduledThreadPoolExecutor.java:294) \[na:1.8.0\_131\]  at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1142) \[na:1.8.0\_131\]  at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:617) \[na:1.8.0\_131\]  at java.lang.Thread.run(Thread.java:748) \[na:1.8.0\_131\]

我们看到“hello start!” 输出了三次，后面就没有输出了，而是直接输出了fallback 里的日志。证明实验成果。

本周关于hystrix我们就介绍到这里，如果不对之处欢迎指正交流！

![https://mmbiz.qpic.cn/mmbiz\_png/StSSauj2rMpmIK8ar9mNGKzwz57xsibVBmibra1bmQZnicgx5v5fyofianUWWibP2mwT3Yy2E0VkOEMaEFPILHaVHIA/640?wx\_fmt=png][https_mmbiz.qpic.cn_mmbiz_png_StSSauj2rMpmIK8ar9mNGKzwz57xsibVBmibra1bmQZnicgx5v5fyofianUWWibP2mwT3Yy2E0VkOEMaEFPILHaVHIA_640_wx_fmt_png]

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[https_mmbiz.qpic.cn_mmbiz_png_StSSauj2rMria8AP4IXpMYxcHvJtKw84t2giaCZB7mfn2qY4O3icuxMqSqlIKLkKQlIBgXR4kD7FOhNL5VCKUz2NA_640_wx_fmt_png]: https://imgconvert.csdnimg.cn/aHR0cHM6Ly9tbWJpei5xcGljLmNuL21tYml6X3BuZy9TdFNTYXVqMnJNcmlhOEFQNElYcE1ZeGNIdkp0S3c4NHQyZ2lhQ1pCN21mbjJxWTRPM2ljdXhNcVNxbElLTGtLUWxJQmdYUjRrRDdGT2hOTDVWQ0tVejJOQS82NDA_d3hfZm10PXBuZw?x-oss-process=image/format,png
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