centos下tomcat无故关闭

这几天tomcat在跑一段时间后就无故自动关闭了，不知道什么情况。
服务器访问量现在不大——非常小。
没有人对服务器进行操作。
tomcat日志：
2013-12-25 21:30:00 org.apache.coyote.http11.Http11AprProtocol pause
信息: Pausing Coyote HTTP/1.1 on http-8080
2013-12-25 21:30:00 org.apache.coyote.ajp.AjpAprProtocol pause
信息: Pausing Coyote AJP/1.3 on ajp-8009
2013-12-25 21:30:01 org.apache.catalina.core.StandardService stop
信息: Stopping service Catalina
2013-12-25 21:30:01 INFO XmlWebApplicationContext:815 - Closing org.springframework.web.context.support.XmlWebApplicationContext@548997d1: display name [Root WebApplicationContext]; startup date [Wed Dec 25 21:18:33 CST 2013]; root of context hierarchy
2013-12-25 21:30:01 INFO DefaultListableBeanFactory:421 - Destroying singletons in org.springframework.beans.factory.support.DefaultListableBeanFactory@33238785: defining beans [gpwAreaInfoService,gpwBulletinInfoService,gpwLinkInfoService,gpwResearchInfoService,gpwResearchValueService,gpwIpInfoService,gpwLeavewordService,cmsNewsColumnService,cmsNewsInfoService,cmsTemplateInfoService,cmsAdInfoService,cmsSpecialInfoService,cmsPageInfoService,cmsPageBlockService,cmsPageConditionService,sysCdsBaseService,sysCodeDataService,sysObjLinkService,sysObjService,sysOptionService,areaTalksService,areaTalkService,areaResourcesService,areaTalksUserService,areaWorkMemberService,areaUnitService,areaUnitsService,areaCommentService,jyzlService,areaCommentAnnexService,springApplicationContext,txProxyTemplate,transactionManager,baseDAO,DAO,jyzlDAO,dataSource,mailSender,propertyConfigurer,remoteRegister,userService,resGateway,staticsService,sysUserInfoService,sysUnitInfoService,sysVisitLogService,eduResColumnService,eduResInfoService,resInfoService,friendInfoService,friendQuestionService,teacherCourseService,teacherScheduleService,collectiveLessonService,collectiveTypeService,collectiveUserTraceService,classUserService,classInfoService,commentInfoService,lessonService,lessionMemberService,recordInfoService,roomInfoService,discussInfoService,favoriteColumnService,favoriteInfoService,jxjhTeachPlanConfigService,jxjhTeachPlanDraftService,jxjhTeachPlanFlagService,jxjhTeachPlanInfoService,jxjhTeachPlanService,browseRecordService,choiceFilesService,archiveColumnService,customFilesService,archiveColumnNameService,archiveStateService,archiveCheckService,documentService,updateService,eduResInfoDataStatics,resInfoDataStatics,friendQuestionDataStatics,sysUserInfoDataStatics,collectiveLessionDataStatics,defineTable,forumInfoService,forumCommentService,forumUsertraceService,sessionFactory,hibernateProperties]; root of factory hierarchy
2013-12-25 21:30:01 INFO LocalSessionFactoryBean:246 - Closing Hibernate SessionFactory
2013-12-25 21:30:01 INFO SessionFactoryImpl:853 - closing
2013-12-25 21:30:02 org.apache.catalina.loader.WebappClassLoader clearReferencesJdbc
严重: The web application [] registered the JDBC driver [com.mysql.jdbc.Driver] but failed to unregister it when the web application was stopped. To prevent a memory leak, the JDBC Driver has been forcibly unregistered.
2013-12-25 21:30:02 org.apache.catalina.loader.WebappClassLoader clearReferencesThreads
严重: The web application [] appears to have started a thread named [Abandoned connection cleanup thread] but has failed to stop it. This is very likely to create a memory leak.
2013-12-25 21:30:02 org.apache.coyote.http11.Http11AprProtocol destroy
信息: Stopping Coyote HTTP/1.1 on http-8080
2013-12-25 21:30:02 org.apache.coyote.ajp.AjpAprProtocol destroy