Hystrix报错java.util.concurrent.TimeoutException: null
完整错误如下：
java.util.concurrent.TimeoutException: null at com.netflix.hystrix.AbstractCommand.handleTimeoutViaFallback(AbstractCommand.java:997) ~[hystrix-core-1.5.18.jar:1.5.18] at com.netflix.hystrix.AbstractCommand.access$500(AbstractCommand.java:60) ~[hystrix-core-1.5.18.jar:1.5.18] at com.netflix.hystrix.AbstractCommand$12.call(AbstractCommand.java:609) ~[hystrix-core-1.5.18.jar:1.5.18] at com.netflix.hystrix.AbstractCommand$12.call(AbstractCommand.java:601) ~[hystrix-core-1.5.18.jar:1.5.18] at rx.internal.operators.OperatorOnErrorResumeNextViaFunction$4.onError(OperatorOnErrorResumeNextViaFunction.java:140) ~[rxjava-1.3.8.jar:1.3.8] at rx.internal.operators.OnSubscribeDoOnEach$DoOnEachSubscriber.onError(OnSubscribeDoOnEach.java:87) ~[rxjava-1.3.8.jar:1.3.8] at rx.internal.operators.OnSubscribeDoOnEach$DoOnEachSubscriber.onError(OnSubscribeDoOnEach.java:87) ~[rxjava-1.3.8.jar:1.3.8] at com.netflix.hystrix.AbstractCommand$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) ~[?:1.8.0_221] at java.util.concurrent.FutureTask.runAndReset(FutureTask.java:308) ~[?:1.8.0_221] at java.util.concurrent.ScheduledThreadPoolExecutor$ScheduledFutureTask.access$301(ScheduledThreadPoolExecutor.java:180) ~[?:1.8.0_221] at java.util.concurrent.ScheduledThreadPoolExecutor$ScheduledFutureTask.run(ScheduledThreadPoolExecutor.java:294) ~[?:1.8.0_221] at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1149) ~[?:1.8.0_221] at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:624) ~[?:1.8.0_221] at java.lang.Thread.run(Thread.java:748)[?:1.8.0_221]
问了度娘，有关闭断路功能的，有断路时间调长的，完全不在点上，我的目的是测试 Hystrix 断路器功能，都关闭了，我还咋验证。后来发现在这个报错之上还有一行错误：
com.netflix.hystrix.contrib.javanica.command.GenericCommand.getFallback 80 - failed to processed fallback is the method: 'failHi'.
调试 com.netflix.hystrix.contrib.javanica.command.GenericCommand.getFallback 方法，发现是断路 @HystrixCommand 注解定义 fallbackMethod 方法反射调用 failHi 失败，再次调试报错的 failHi 方法，最终发现是 failHi 方法中出现了 RuntimeException 异常，错误的实例代码如下：
@HystrixCommand(fallbackMethod = "failHi") @ResponseBody @GetMapping("/hi3") public String hi3() { return restTemplate.getForObject("http://127.0.0.1:" + port + "/res", String.class);}public String failHi() {
try {
return doThings();
} catch (Exception e) {
throw new RuntimeException("失败，" + e.getMessage());
}
}