MingJunDuan
Hi，你好，提个问题，guava的EventBus.register()注册时，会最终调用Subscriber.create()方法，如下，会判断方法上是否有AllowConcurrentEvents注解，来创建不同的Subscriber，如果没有AllowConcurrentEvents注解则创建SynchronizedSubscriber，而这个类的invokeSubscriberMethod方法中使用了synchronized作为同步，所以如果只是加上注解Subscribe在方法上，那么非真正的并发. ```bash ... static Subscriber create(EventBus bus, Object listener, Method method) { return (Subscriber)(isDeclaredThreadSafe(method) ? new Subscriber(bus, listener, method) : new Subscriber.SynchronizedSubscriber(bus, listener, method)); } ... private static boolean isDeclaredThreadSafe(Method method) { return method.getAnnotation(AllowConcurrentEvents.class) != null; } @VisibleForTesting static final class SynchronizedSubscriber extends Subscriber { private SynchronizedSubscriber(EventBus bus, Object target, Method method) { super(bus, target, method, null); } void invokeSubscriberMethod(Object event) throws InvocationTargetException { synchronized(this) { super.invokeSubscriberMethod(event); } } } ... ```