java.lang.IllegalStateException: Cannot create a session after the response has been committed

[Brian Braun Mitman]

Hi,

First of all, I'm using Tomcat 6.0.29 (the latest as of September 2010), Struts and other technologies not relevant here.

My website runs fine 99% of the time, but several times per day I get an error in my Tomcat Log, so it is an sporadic issue. I don't know the reason. My code is separated in model/view/controller, given that I'm using Struts, so my code has been correctly separated in layers. This error happens in several JSP pages.
As far as I can understand, Tomcat generates a Java class (a servlet) for every JSP (well, everybody know that I guess). When my problem arrises, an exception is being thrown when the corresponding generated servlet tries to run the "_jspService()" method that uses a lot of "out.write()" methods to send the output to the response. An exception is being thrown for some reason, and then my log gets the error trace.
Anybody knows what is going on?


This is the error in the log:

Sep 21, 2010 3:18:42 PM org.apache.jasper.runtime.JspFactoryImpl internalGetPageContext
SEVERE: Exception initializing page context
java.lang.IllegalStateException: Cannot create a session after the response has been committed <------------Which session is my code creating? where? Why is this sporadic?
at org.apache.catalina.connector.Request.doGetSession(Request.java:2377)
at org.apache.catalina.connector.Request.getSession(Request.java:2097)
at org.apache.catalina.connector.RequestFacade.getSession(RequestFacade.java:833)
at javax.servlet.http.HttpServletRequestWrapper.getSession(HttpServletRequestWrapper.java:216)
at org.apache.catalina.core.ApplicationHttpRequest.getSession(ApplicationHttpRequest.java:547)
at javax.servlet.http.HttpServletRequestWrapper.getSession(HttpServletRequestWrapper.java:216)
at org.apache.catalina.core.ApplicationHttpRequest.getSession(ApplicationHttpRequest.java:547)
at javax.servlet.http.HttpServletRequestWrapper.getSession(HttpServletRequestWrapper.java:216)
at org.apache.catalina.core.ApplicationHttpRequest.getSession(ApplicationHttpRequest.java:547)
at org.apache.catalina.core.ApplicationHttpRequest.getSession(ApplicationHttpRequest.java:493)
at org.apache.jasper.runtime.PageContextImpl._initialize(PageContextImpl.java:146)
at org.apache.jasper.runtime.PageContextImpl.initialize(PageContextImpl.java:124)
at org.apache.jasper.runtime.JspFactoryImpl.internalGetPageContext(JspFactoryImpl.java:107)
at org.apache.jasper.runtime.JspFactoryImpl.getPageContext(JspFactoryImpl.java:63)
at org.apache.jsp.WEB_002dINF.pages.utility.Error_jsp._jspService(Error_jsp.java:49) <-------------- This is the JSP page where all my JSP pages redirect when something goes wrong
at org.apache.jasper.runtime.HttpJspBase.service(HttpJspBase.java:70)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:717)
at org.apache.jasper.servlet.JspServletWrapper.service(JspServletWrapper.java:377)
at org.apache.jasper.servlet.JspServlet.serviceJspFile(JspServlet.java:313)
at org.apache.jasper.servlet.JspServlet.service(JspServlet.java:260)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:717)
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:646)
at org.apache.catalina.core.ApplicationDispatcher.doInclude(ApplicationDispatcher.java:551)
at org.apache.catalina.core.ApplicationDispatcher.include(ApplicationDispatcher.java:488)
at org.apache.jasper.runtime.JspRuntimeLibrary.include(JspRuntimeLibrary.java:968)
at org.apache.jasper.runtime.PageContextImpl.include(PageContextImpl.java:621)
at org.apache.jasper.runtime.PageContextImpl.doHandlePageException(PageContextImpl.java:820)
at org.apache.jasper.runtime.PageContextImpl.handlePageException(PageContextImpl.java:791)
at org.apache.jsp.WEB_002dINF.pages.ProductsForModel_jsp._jspService(ProductsForModel_jsp.java:1137) <------- In this case, the problem happened in my page "ProductsForModel.jsp"
at org.apache.jasper.runtime.HttpJspBase.service(HttpJspBase.java:70)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:717)
at org.apache.jasper.servlet.JspServletWrapper.service(JspServletWrapper.java:377)
at org.apache.jasper.servlet.JspServlet.serviceJspFile(JspServlet.java:313)
at org.apache.jasper.servlet.JspServlet.service(JspServlet.java:260)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:717)
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:646)
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:1056)
at org.apache.struts.action.RequestProcessor.processForwardConfig(RequestProcessor.java:388)
at org.apache.struts.action.RequestProcessor.process(RequestProcessor.java:231)
at org.apache.struts.action.ActionServlet.process(ActionServlet.java:1164)
at org.apache.struts.action.ActionServlet.doGet(ActionServlet.java:397)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:617)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:717)
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:646)
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 com.zlatkovic.HttpRedirectFilter.doFilter(HttpRedirectFilter.java:229)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:235)
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:191)
at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:127)
at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:102)
at org.apache.catalina.valves.AccessLogValve.invoke(AccessLogValve.java:555)
at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:109)
at org.apache.catalina.valves.RequestFilterValve.process(RequestFilterValve.java:276)
at org.apache.catalina.valves.RemoteAddrValve.invoke(RemoteAddrValve.java:81)
at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:298)
at org.apache.coyote.http11.Http11Processor.process(Http11Processor.java:857)
at org.apache.coyote.http11.Http11Protocol$Http11ConnectionHandler.process(Http11Protocol.java:588)
at org.apache.tomcat.util.net.JIoEndpoint$Worker.run(JIoEndpoint.java:489)
at java.lang.Thread.run(Thread.java:619)

[William Brogden]

A response is committed when the first buffer of output stream has to be flushed. Since a session requires a header to be set, this can't be done after the first buffer is sent. Having variable amounts of content would make this a sporadic error.

If you need a session you should ensure it is created early.

Bill

[Brian Braun Mitman]

Hi William,

What could be the reasons for a flush to happen?
I have learnt that maybe my 8K buffer gets full in some cases (as you said, my contect is dynamic and sometimes could be large). In that case, I have understanded that a full buffer triggers a commit, and when that happens the JSP error page can not do its job and then "java.lang.IllegalStateException: Cannot create a session after the response has been committed" happens. OK, but is there any other possible reason for the early commit?
My session is created early enough, and in fact the JSP page creates it if necessary, by default.

Thanks a lot!!!

[Tim Holloway]

I wouldn't place too much emphasis on "buffer flush". Even it it's a factor, it would mean you're doing something wrong.

The most common IllegalStateExceptions for J2EE have to do with people creating headers AFTER they've written to the response stream. Never mind buffer flush. If you want reliable operation, write the headers FIRST! Which can be a little tricky when you're creating the headers in a JSP, since there's an implied write going on from the very first line, so it's a good idea to place the header-generating scriptlet before any HTML tags and most definitely before any explicit write commands. Or better yet, use the tag language if possible.

However, your message says "Cannot create a session". This one's a little puzzling. My best guesses on this one are:

A. You're doing an explict close on the response writer. Don't do that. The framework will close the stream.

B. You're doing an explicit flush on the response writer. Avoid that. And definitely explicitly force the session to be created first, if you can't.

C. Dang it, I've forgotten. I hate being senile!

Also, despite your assertion that the version of Struts doesn't matter, I'd search the Struts issues just in case you've run across a version of Struts with a bug in it, since this is a little off-the-wall.