tomcat 经常死掉,一天有时候都两次,请问是什么原因?

严重: Servlet.service() for servlet action threw exception
javax.servlet.jsp.JspException
at net.hlj.frame.tags.jdbc.PrepareStatementTag.doAfterBody(PrepareStatementTag.java:44)
at org.apache.jsp.jsp.cxTopic_jsp._jspService(cxTopic_jsp.java:3362)
at org.apache.jasper.runtime.HttpJspBase.service(HttpJspBase.java:70)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:803)
at org.apache.jasper.servlet.JspServletWrapper.service(JspServletWrapper.java:374)
at org.apache.jasper.servlet.JspServlet.serviceJspFile(JspServlet.java:337)
at org.apache.jasper.servlet.JspServlet.service(JspServlet.java:266)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:803)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:290)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206)
at org.apache.catalina.core.ApplicationDispatcher.invoke(ApplicationDispatcher.java:630)
at org.apache.catalina.core.ApplicationDispatcher.processRequest(ApplicationDispatcher.java:436)
at org.apache.catalina.core.ApplicationDispatcher.doForward(ApplicationDispatcher.java:374)
at org.apache.catalina.core.ApplicationDispatcher.forward(ApplicationDispatcher.java:302)
at org.apache.struts.action.RequestProcessor.doForward(RequestProcessor.java:1063)
at org.apache.struts.action.RequestProcessor.processForwardConfig(RequestProcessor.java:386)
at org.apache.struts.action.RequestProcessor.process(RequestProcessor.java:229)
at org.apache.struts.action.ActionServlet.process(ActionServlet.java:1194)
at org.apache.struts.action.ActionServlet.doGet(ActionServlet.java:414)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:690)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:803)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:290)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206)
at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:233)
at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:175)
at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:128)
at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:102)
at org.apache.catalina.valves.AccessLogValve.invoke(AccessLogValve.java:568)
at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:109)
at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:286)
at org.apache.coyote.http11.Http11Processor.process(Http11Processor.java:844)
at org.apache.coyote.http11.Http11Protocol$Http11ConnectionHandler.process(Http11Protocol.java:583)
at org.apache.tomcat.util.net.JIoEndpoint$Worker.run(JIoEndpoint.java:447)
at java.lang.Thread.run(Thread.java:619)
2009-3-25 11:56:55 org.apache.catalina.core.ApplicationDispatcher invoke
严重: Servlet.service() for servlet jsp threw exception
java.lang.NullPointerException
at com.microsoft.util.UtilException.getLocalizedReason(Unknown Source)
at com.microsoft.util.UtilException.<init>(Unknown Source)
at com.microsoft.util.UtilDepacketizingDataProvider.getArrayOfBytes(Unknown Source)
at com.microsoft.util.UtilPagedTempBuffer.write(Unknown Source)
at com.microsoft.util.UtilPagedTempBuffer.write(Unknown Source)
at com.microsoft.util.UtilByteArrayDataProvider.receive(Unknown Source)
at com.microsoft.util.UtilByteOrderedDataReader.receive(Unknown Source)
at com.microsoft.jdbc.sqlserver.tds.TDSRPCRequest.submitRequest(Unknown Source)
at com.microsoft.jdbc.sqlserver.tds.TDSCursorRequest.sendCursorFetch(Unknown Source)
at com.microsoft.jdbc.sqlserver.tds.TDSCursorRequest.fetchAbsolute(Unknown Source)
at com.microsoft.jdbc.sqlserver.SQLServerImplResultSetServerSideCursor.positionCursor(

使用Jprofiler做性能压力测试,软件不做性能测试就是半成品

我们都上线很长时间了,但是经常死掉,不知道为什么啊?