最近項目里面,用了spring的定時任務,一直以來,項目運行的不錯。定時器也能正常使用。可是,今天啟動項目測試的時候,盯着啟動Log看了一陣子,突然間發現,啟動的Log中居然有一個異常,雖然一閃而過,但是那熟悉的異常格式還是讓我渾身一顫。這個項目一直運行的很好啊,沒發現有什么問題,怎么會出現異常呢?
於是我仔細的翻啊翻啊,查啊找啊,嘿,還真的找到了兩個異常:
- [2016-10-12 22:49:10,184] [DEBUG] (ScheduledAnnotationBeanPostProcessor.java:finishRegistration:207)
- Could not find default TaskScheduler bean
- org.springframework.beans.factory.NoSuchBeanDefinitionException: No qualifying bean of type [org.springframework.scheduling.TaskScheduler] is defined
- at org.springframework.beans.factory.support.DefaultListableBeanFactory.getBean(DefaultListableBeanFactory.java:372)
- at org.springframework.beans.factory.support.DefaultListableBeanFactory.getBean(DefaultListableBeanFactory.java:332)
- at org.springframework.scheduling.annotation.ScheduledAnnotationBeanPostProcessor.finishRegistration(ScheduledAnnotationBeanPostProcessor.java:192)
- at org.springframework.scheduling.annotation.ScheduledAnnotationBeanPostProcessor.onApplicationEvent(ScheduledAnnotationBeanPostProcessor.java:171)
- at org.springframework.scheduling.annotation.ScheduledAnnotationBeanPostProcessor.onApplicationEvent(ScheduledAnnotationBeanPostProcessor.java:86)
- at org.springframework.context.event.SimpleApplicationEventMulticaster.invokeListener(SimpleApplicationEventMulticaster.java:163)
- at org.springframework.context.event.SimpleApplicationEventMulticaster.multicastEvent(SimpleApplicationEventMulticaster.java:136)
- at org.springframework.context.support.AbstractApplicationContext.publishEvent(AbstractApplicationContext.java:381)
- at org.springframework.context.support.AbstractApplicationContext.publishEvent(AbstractApplicationContext.java:335)
- at org.springframework.context.support.AbstractApplicationContext.finishRefresh(AbstractApplicationContext.java:855)
- at org.springframework.context.support.AbstractApplicationContext.refresh(AbstractApplicationContext.java:541)
- at org.springframework.web.context.ContextLoader.configureAndRefreshWebApplicationContext(ContextLoader.java:444)
- at org.springframework.web.context.ContextLoader.initWebApplicationContext(ContextLoader.java:326)
- at org.springframework.web.context.ContextLoaderListener.contextInitialized(ContextLoaderListener.java:107)
- at org.apache.catalina.core.StandardContext.listenerStart(StandardContext.java:4812)
- at org.apache.catalina.core.StandardContext.startInternal(StandardContext.java:5255)
- at org.apache.catalina.util.LifecycleBase.start(LifecycleBase.java:147)
- at org.apache.catalina.core.ContainerBase$StartChild.call(ContainerBase.java:1408)
- at org.apache.catalina.core.ContainerBase$StartChild.call(ContainerBase.java:1398)
- at java.util.concurrent.FutureTask.run(FutureTask.java:266)
- at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1142)
- at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:617)
- at java.lang.Thread.run(Thread.java:745)
- [2016-10-12 22:49:10,188] [DEBUG] (ScheduledAnnotationBeanPostProcessor.java:finishRegistration:219)
- Could not find default ScheduledExecutorService bean
- org.springframework.beans.factory.NoSuchBeanDefinitionException: No qualifying bean of type [org.springframework.scheduling.TaskScheduler] is defined
- at org.springframework.beans.factory.support.DefaultListableBeanFactory.getBean(DefaultListableBeanFactory.java:372)
- at org.springframework.beans.factory.support.DefaultListableBeanFactory.getBean(DefaultListableBeanFactory.java:332)
- at org.springframework.scheduling.annotation.ScheduledAnnotationBeanPostProcessor.finishRegistration(ScheduledAnnotationBeanPostProcessor.java:192)
- at org.springframework.scheduling.annotation.ScheduledAnnotationBeanPostProcessor.onApplicationEvent(ScheduledAnnotationBeanPostProcessor.java:171)
- at org.springframework.scheduling.annotation.ScheduledAnnotationBeanPostProcessor.onApplicationEvent(ScheduledAnnotationBeanPostProcessor.java:86)
- at org.springframework.context.event.SimpleApplicationEventMulticaster.invokeListener(SimpleApplicationEventMulticaster.java:163)
- at org.springframework.context.event.SimpleApplicationEventMulticaster.multicastEvent(SimpleApplicationEventMulticaster.java:136)
- at org.springframework.context.support.AbstractApplicationContext.publishEvent(AbstractApplicationContext.java:381)
- at org.springframework.context.support.AbstractApplicationContext.publishEvent(AbstractApplicationContext.java:335)
- at org.springframework.context.support.AbstractApplicationContext.finishRefresh(AbstractApplicationContext.java:855)
- at org.springframework.context.support.AbstractApplicationContext.refresh(AbstractApplicationContext.java:541)
- at org.springframework.web.context.ContextLoader.configureAndRefreshWebApplicationContext(ContextLoader.java:444)
- at org.springframework.web.context.ContextLoader.initWebApplicationContext(ContextLoader.java:326)
- at org.springframework.web.context.ContextLoaderListener.contextInitialized(ContextLoaderListener.java:107)
- at org.apache.catalina.core.StandardContext.listenerStart(StandardContext.java:4812)
- at org.apache.catalina.core.StandardContext.startInternal(StandardContext.java:5255)
- at org.apache.catalina.util.LifecycleBase.start(LifecycleBase.java:147)
- at org.apache.catalina.core.ContainerBase$StartChild.call(ContainerBase.java:1408)
- at org.apache.catalina.core.ContainerBase$StartChild.call(ContainerBase.java:1398)
- at java.util.concurrent.FutureTask.run(FutureTask.java:266)
- at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1142)
- at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:617)
- at java.lang.Thread.run(Thread.java:745)
暈啊,很明顯這是定時任務的異常啊。可是定時任務明明能夠正常運行啊,怎么回事?
嘗試着刪掉了所有的定時任務配置,果然異常消失了。但是只要啟用任何一個定時任務,異常都會再次出現。這可真可怕。作為一個強迫症患者,不能放任這樣的異常存在,於是仔細的查找了半天,卻依舊沒有結果。最后只好放大招,讀spring的源碼啦,這一讀,可好,差點沒把我郁悶死。
為什么郁悶呢? 不知道讀這篇文章的朋友們有沒有細心的,有沒有注意這兩個異常有一個非常特別的地方。什么地方呢? 這兩個異常的級別,不是ERROR 也不是 WARNING
居然是DEBUG
原來,Spring的定時任務調度器會嘗試獲取一個注冊過的 task scheduler來做任務調度,它會嘗試通過BeanFactory.getBean的方法來獲取一個注冊過的scheduler bean,獲取的步驟如下:
1.嘗試從配置中找到一個TaskScheduler Bean
2.尋找ScheduledExecutorService Bean
3.使用默認的scheduler
前兩步,如果找不到的話,就會以debug的方式拋出異常,分別是:
logger.debug("Could not find default TaskScheduler bean", ex);
logger.debug("Could not find default ScheduledExecutorService bean", ex);
所以,日志中打印出來的兩個異常,根本不是什么錯誤信息,也不會影響定時器的使用,只不過是spring的自己打印的一些信息罷了,不過沒搞明白,為什么非要用異常的方式打出來,估計是為了看這清晰點吧。也或者,這里面有一些重要的信息需要提示開發者。具體是什么原因,只能有機會進一步再去了解了。
