给鲨鱼的2.0 提个问题

系统启动后不去请求，
放久了，
就出现这个错误

五月 25, 2016 4:36:22 下午 org.apache.catalina.session.StandardSession expire
严重: Session event listener threw exception
org.apache.shiro.UnavailableSecurityManagerException: No SecurityManager accessible to the calling code, either bound to the org.apache.shiro.util.ThreadContext or as a vm static singleton.  This is an invalid application configuration.
	at org.apache.shiro.SecurityUtils.getSecurityManager(SecurityUtils.java:123)
	at org.apache.shiro.subject.Subject$Builder.<init>(Subject.java:627)
	at org.apache.shiro.SecurityUtils.getSubject(SecurityUtils.java:56)
	at cn.wizzer.common.mvc.listener.MySessionListener.sessionDestroyed(MySessionListener.java:38)
	at org.apache.catalina.session.StandardSession.expire(StandardSession.java:799)
	at org.apache.catalina.session.StandardSession.isValid(StandardSession.java:647)
	at org.apache.catalina.session.ManagerBase.processExpires(ManagerBase.java:660)
	at org.apache.catalina.session.ManagerBase.backgroundProcess(ManagerBase.java:645)
	at org.apache.catalina.core.ContainerBase.backgroundProcess(ContainerBase.java:1349)
	at org.apache.catalina.core.ContainerBase$ContainerBackgroundProcessor.processChildren(ContainerBase.java:1543)
	at org.apache.catalina.core.ContainerBase$ContainerBackgroundProcessor.processChildren(ContainerBase.java:1553)
	at org.apache.catalina.core.ContainerBase$ContainerBackgroundProcessor.processChildren(ContainerBase.java:1553)
	at org.apache.catalina.core.ContainerBase$ContainerBackgroundProcessor.run(ContainerBase.java:1521)
	at java.lang.Thread.run(Unknown Source)