项目启动一段时间后，进入初始页面，会出现java.util.EmptyStackException异常，刷新一次后异常就消失了。

An exception has occurred.  

You may continue by restarting the session.

[ +/- ] Exception: There was an error borrowing the page with key PageKey[_pageName='Home' , _locale=zh_CN ] from the page pool.

org.apache.hivemind.ApplicationRuntimeException

There was an error borrowing the page with key PageKey[_pageName='Home' , _locale=zh_CN ] from the page pool.

[ +/- ] Exception:

java.util.EmptyStackException

Stack Trace:

java.util.Stack.peek(Unknown Source) java.util.Stack.pop(Unknown Source) org.apache.tapestry.pageload.PageLoader.endConstructComponent(PageLoader.java:469) org.apache.tapestry.pageload.PageLoader.constructComponent(PageLoader.java:424) org.apache.tapestry.pageload.PageLoader.loadPage(PageLoader.java:639) $IPageLoader_118e361a96c.loadPage($IPageLoader_118e361a96c.java) $IPageLoader_118e361a96d.loadPage($IPageLoader_118e361a96d.java) org.apache.tapestry.pageload.PageSource.makeObject(PageSource.java:153) org.apache.commons.pool.impl.GenericKeyedObjectPool.borrowObject(GenericKeyedObjectPool.java:797) org.apache.tapestry.pageload.PageSource.getPage(PageSource.java:177) $IPageSource_118e361a8bf.getPage($IPageSource_118e361a8bf.java) org.apache.tapestry.engine.RequestCycle.loadPage(RequestCycle.java:239) org.apache.tapestry.engine.RequestCycle.getPage(RequestCycle.java:226) org.apache.tapestry.engine.RequestCycle.activate(RequestCycle.java:559) org.apache.tapestry.engine.HomeService.service(HomeService.java:66) $IEngineService_118e361a954.service($IEngineService_118e361a954.java) org.apache.tapestry.services.impl.EngineServiceOuterProxy.service(EngineServiceOuterProxy.java:72) org.apache.tapestry.engine.AbstractEngine.service(AbstractEngine.java:237) org.apache.tapestry.services.impl.InvokeEngineTerminator.service(InvokeEngineTerminator.java:54) $WebRequestServicer_118e361a92d.service($WebRequestServicer_118e361a92d.java) $WebRequestServicer_118e361a929.service($WebRequestServicer_118e361a929.java) org.apache.tapestry.services.impl.WebRequestServicerPipelineBridge.service(WebRequestServicerPipelineBridge.java:61) $ServletRequestServicer_118e361a90f.service($ServletRequestServicer_118e361a90f.java) org.apache.tapestry.request.DecodedRequestInjector.service(DecodedRequestInjector.java:55) $ServletRequestServicerFilter_118e361a90b.service($ServletRequestServicerFilter_118e361a90b.java) $ServletRequestServicer_118e361a911.service($ServletRequestServicer_118e361a911.java) org.apache.tapestry.multipart.MultipartDecoderFilter.service(MultipartDecoderFilter.java:52) $ServletRequestServicerFilter_118e361a909.service($ServletRequestServicerFilter_118e361a909.java) $ServletRequestServicer_118e361a911.service($ServletRequestServicer_118e361a911.java) org.apache.tapestry.services.impl.SetupRequestEncoding.service(SetupRequestEncoding.java:53) $ServletRequestServicerFilter_118e361a90d.service($ServletRequestServicerFilter_118e361a90d.java) $ServletRequestServicer_118e361a911.service($ServletRequestServicer_118e361a911.java) $ServletRequestServicer_118e361a903.service($ServletRequestServicer_118e361a903.java) org.apache.tapestry.ApplicationServlet.doService(ApplicationServlet.java:126) org.apache.tapestry.ApplicationServlet.doGet(ApplicationServlet.java:103) javax.servlet.http.HttpServlet.service(HttpServlet.java:689) javax.servlet.http.HttpServlet.service(HttpServlet.java:802) org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:252) org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:173) com.myso.util.SetCharacterEncodingFilter.doFilter(SetCharacterEncodingFilter.java:34) org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:202) org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:173) org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:213) org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:178) org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:126) org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:105) org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:107) org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:148) org.apache.coyote.http11.Http11Processor.process(Http11Processor.java:869) org.apache.coyote.http11.Http11BaseProtocol$Http11ConnectionHandler.processConnection(Http11BaseProtocol.java:664) org.apache.tomcat.util.net.PoolTcpEndpoint.processSocket(PoolTcpEndpoint.java:527) org.apache.tomcat.util.net.LeaderFollowerWorkerThread.runIt(LeaderFollowerWorkerThread.java:80) org.apache.tomcat.util.threads.ThreadPool$ControlRunnable.run(ThreadPool.java:684) java.lang.Thread.run(Unknown Source)

请问，异常发生的原因可能是什么？什么导致了空栈的错误？