@Async

@EnableAsync

AsyncConfigurationSelector

ProxyAsyncConfiguration

AsyncAnnotationBeanPostProcessor

1. AbstractBeanFactoryAwareAdvisingPostProcessor

1.1. AbstractAdvisingBeanPostProcessor

1.1.1. protected boolean isEligible(Object bean, String beanName)
确定是否需要代理

AbstractAsyncConfiguration

1.循环依赖问题, 添加@lazy

2.SimpleAsyncTaskExecutor
为每个任务新起一个线程
默认线程数不做限制
不复用线程

需要指定线程池