现象：
昨天突然线上很多接口获取失败，通过 kibana发现大量异常，具体异常信息：
...into fallback. Rejected command because thread-pool queueSize is at rejection threshold.
异常代码出处：
@FeignClient(name = "api", fallbackFactory = LoadBalancingFallbackFactory.class)
public interface LoadBalancingFeignClient {
@PostMapping(value = "/api/loadBalancing/server")
Result currentServer();
}
@Slf4j
@Component
public class LoadBalancingFallbackFactory implements FallbackFactory<LoadBalancingFeignClient> {
@Override
public LoadBalancingFeignClient create(Throwable throwable) {
final String msg = throwable.getMessage();
return () -> {
log.error("loadBalancingFeignClient currentServer into fallback. {}", msg);
return Result.error();
};****
}
}
原因：
看到这里已经很明显了，是由于hystrix线程池不够用，直接熔断导致的。
项目apollo配置：
hystrix.command.default.execution.isolation.thread.timeoutInMilliseconds = 3500 hystrix.threadpool.default.maxQueueSize = 60 hystrix.threadpool.default.queueSizeRejectionThreshold = 40
hystrix参数简析：
maxQueueSize：线程池大小，默认为-1，创建的队列是SynchronousQueue，如果设置大于0则根据其大小创建LinkedBlockingQueue。
queueSizeRejectionThreshold：动态控制线程池队列的上限，即使maxQueueSize没有达到，达到queueSizeRejectionThreshold该值后，请求也会被拒绝，默认值5
相关源码：
hystrix-core-1.5.12-sources.jar!/com/netflix/hystrix/strategy/concurrency/HystrixContextScheduler.java
private class HystrixContextSchedulerWorker extends Worker {
private final Worker worker;
private HystrixContextSchedulerWorker(Worker actualWorker) {
this.worker = actualWorker;
}
@Override
public void unsubscribe() {
worker.unsubscribe();
}
@Override
public boolean isUnsubscribed() {
return worker.isUnsubscribed();
}
@Override
public Subscription schedule(Action0 action, long delayTime, TimeUnit unit) {
if (threadPool != null) {
if (!threadPool.isQueueSpaceAvailable()) {
throw new RejectedExecutionException("Rejected command because thread-pool queueSize is at rejection threshold.");
}
}
return worker.schedule(new HystrixContexSchedulerAction(concurrencyStrategy, action), delayTime, unit);
}
@Override
public Subscription schedule(Action0 action) {
if (threadPool != null) {
if (!threadPool.isQueueSpaceAvailable()) {
throw new RejectedExecutionException("Rejected command because thread-pool queueSize is at rejection threshold.");
}
}
return worker.schedule(new HystrixContexSchedulerAction(concurrencyStrategy, action));
}
}
解决办法：
