先来看一下异常信息,启动tomcat时就报错:
2015-3-20 15:22:39 org.apache.catalina.core.StandardContext listenerStart 严重: Exception sending context initialized event to listener instance of class com.***.***.action.GateWayMonitorListener java.util.concurrent.RejectedExecutionException at java.util.concurrent.ThreadPoolExecutor$AbortPolicy.rejectedExecution (ThreadPoolExecutor.java:1774) at java.util.concurrent.ThreadPoolExecutor.reject(ThreadPoolExecutor.jav a:768) at java.util.concurrent.ScheduledThreadPoolExecutor.delayedExecute(Sched uledThreadPoolExecutor.java:215) at java.util.concurrent.ScheduledThreadPoolExecutor.scheduleWithFixedDel ay(ScheduledThreadPoolExecutor.java:443) at com.***.***.action.GateWayMonitorListener .scheduleEmailAndSms(GateWayMonitorListener.java:77) at com.***.***.action.GateWayMonitorListener .contextInitialized(GateWayMonitorListener.java:67) at org.apache.catalina.core.StandardContext.listenerStart(StandardContex t.java:4206) at org.apache.catalina.core.StandardContext.start(StandardContext.java:4 705) at org.apache.catalina.core.ContainerBase.addChildInternal(ContainerBase .java:799) at org.apache.catalina.core.ContainerBase.addChild(ContainerBase.java:77 9) at org.apache.catalina.core.StandardHost.addChild(StandardHost.java:601) at org.apache.catalina.startup.HostConfig.deployDirectory(HostConfig.jav a:1079) at org.apache.catalina.startup.HostConfig.deployDirectories(HostConfig.j ava:1002) at org.apache.catalina.startup.HostConfig.deployApps(HostConfig.java:506 ) at org.apache.catalina.startup.HostConfig.start(HostConfig.java:1317) at org.apache.catalina.startup.HostConfig.lifecycleEvent(HostConfig.java :324) at org.apache.catalina.util.LifecycleSupport.fireLifecycleEvent(Lifecycl eSupport.java:142) at org.apache.catalina.core.ContainerBase.start(ContainerBase.java:1065) at org.apache.catalina.core.StandardHost.start(StandardHost.java:840) at org.apache.catalina.core.ContainerBase.start(ContainerBase.java:1057) at org.apache.catalina.core.StandardEngine.start(StandardEngine.java:463 ) at org.apache.catalina.core.StandardService.start(StandardService.java:5 25) at org.apache.catalina.core.StandardServer.start(StandardServer.java:754 ) at org.apache.catalina.startup.Catalina.start(Catalina.java:595) at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl. java:39) at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAcces sorImpl.java:25) at java.lang.reflect.Method.invoke(Method.java:597) at org.apache.catalina.startup.Bootstrap.start(Bootstrap.java:289) at org.apache.catalina.startup.Bootstrap.main(Bootstrap.java:414) 2015-3-20 15:22:39 org.apache.catalina.core.StandardContext start 严重: Error listenerStart
再来看看相关源码:
public class GateWayMonitorListener implements ServletContextListener, ApplicationContextAware { /** * 设定两个线程,一个用来定期发送巡检短信;另一个定期执行三大运营商网关监控。 */ public static ScheduledExecutorService service = Executors.newScheduledThreadPool(2); public void contextInitialized(ServletContextEvent event) { // 网关监测 GateWayMonitorListener.service.scheduleWithFixedDelay(new MonitorTask(), 60, MonitorConfigCache.lastPollingIntervalSecond, TimeUnit.SECONDS); // 定时每天固定时间发送短信 GateWayMonitorListener.service.scheduleAtFixedRate(new EveryDaySmsTask(), calculateIntialDelay(), GateWayMonitorListener.ONE_DAY_IN_MILLISECONDS, TimeUnit.MILLISECONDS); } } /** * 按新时间间隔重新设置定时任务。 * * @param interval */ public static synchronized void resetMonitorTaskInterval() { // 关闭老的线程池 GateWayMonitorListener.service.shutdownNow(); try { GateWayMonitorListener.service.awaitTermination(60, TimeUnit.SECONDS); } catch (InterruptedException e) { log.warn("InterruptedException when shutdown old threadPool", e); } catch (Exception e) { log.error("other exception when shutdown old threadPool", e); } GateWayMonitorListener.service = Executors.newScheduledThreadPool(2); // 重新设置定时任务。 … }
没有列出的还有另一个类会定时重新加载定时任务的配置文件,如果配置文件修改了定时任务执行的时间设置,则重新配置定时任务,起到热加载配置文件的目的。也就是会调用resetMonitorTaskInterval()方法。
二、 问题分析
Tomcat一启动就报错 RejectedExecutionException,
(1)根据jdk描述何时回抛出这个异常:if the task cannot be scheduled for execution,只是说任务在不能被加入线程池时会抛出这个异常,不够明确。
(2)进一步分析什么时候线程池不能加入线程来执行,如果不是线程池还未被初始化好,线程池已满且策略是超过的会被拒绝外,就是线程池被shutdown了。Tomcat一启动就报错,而且线程池是在最上面static的,那应该就是被shutdown了。查看是否有哪里调用shutdown方法了。
(3)再分析,果然在另一个线程处会调用重新设置线程池的方法resetMonitorTaskInterval(),而且里面调用了shutdown。问题找到了,第一次读配置文件时就触发了重新设置定时任务。这是不行滴。。第一次只算是初始化,后面发现变更才应该重设线程池。但一定要控制同步,保证shutdown之后没有再往旧线程池中加入定时任务。
三、 问题解决
控制线程池的shutdown调用,调用后不能再往线程池里加入线程。