java.lang.IllegalStateException: Exception occurred when flushing data [duplicate]

Question

Possible Duplicate:
Exception occurred when flushing data . What is this and why am I getting this?

The following is a snippet from a filter. It gets the client IP , sets the attribute and then chains the request to a servlet.

@Override
 public void doFilter(ServletRequest request,ServletResponse response,FilterChain chain) 
        throws ServletException,IOException {
    String IP = request.getRemoteAddr();
    request.setAttribute("client IP from the filter", IP);
    chain.doFilter(request, response);
}

The following is a snippet from the servlet which has received a filtered request. It gets the IP , stores it as an another attribute and then dispatches the request to index.jsp .

    @Override
protected void doGet(HttpServletRequest request, HttpServletResponse response)
        throws ServletException, IOException {
    String IP = (String)request.getAttribute("client IP from the filter");
    request.setAttribute("Client IP", IP);
    RequestDispatcher rd = request.getRequestDispatcher("index.jsp");
    rd.forward(request,response);
}

index.jsp , then retrieves the attribute set by the servlet and works upon it.

The servlet is the first thing to run when a website foo.com is first opened. But as I open the website I see this stack trace :

java.lang.IllegalStateException: Exception occurred when flushing data
at com.google.appengine.runtime.Request.process-d6995d0c305e239e(Request.java)
at org.apache.jasper.runtime.PageContextImpl.release(PageContextImpl.java:191)
at org.apache.jasper.runtime.JspFactoryImpl.internalReleasePageContext(JspFactoryImpl.java:118)
at org.apache.jasper.runtime.JspFactoryImpl.access$100(JspFactoryImpl.java:40)
at org.apache.jasper.runtime.JspFactoryImpl$PrivilegedReleasePageContext.run(JspFactoryImpl.java:166)
at java.security.AccessController.doPrivileged(AccessController.java:34)
at org.apache.jasper.runtime.JspFactoryImpl.releasePageContext(JspFactoryImpl.java:75)
at org.apache.jsp.index_jsp._jspService(index_jsp.java:139)
at org.apache.jasper.runtime.HttpJspBase.service(HttpJspBase.java:97)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:717)
at org.mortbay.jetty.servlet.ServletHolder.handle(ServletHolder.java:511)
at org.mortbay.jetty.servlet.ServletHandler.handle(ServletHandler.java:390)
at org.mortbay.jetty.security.SecurityHandler.handle(SecurityHandler.java:216)
at org.mortbay.jetty.servlet.SessionHandler.handle(SessionHandler.java:182)
at org.mortbay.jetty.handler.ContextHandler.handle(ContextHandler.java:765)
at org.mortbay.jetty.webapp.WebAppContext.handle(WebAppContext.java:418)
at org.mortbay.jetty.servlet.Dispatcher.forward(Dispatcher.java:327)
at org.mortbay.jetty.servlet.Dispatcher.forward(Dispatcher.java:126)
at Servlets.FW_FirstSite.doGet(FW_FirstSite.java:27)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:617)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:717)
at org.mortbay.jetty.servlet.ServletHolder.handle(ServletHolder.java:511)
at org.mortbay.jetty.servlet.ServletHandler$CachedChain.doFilter(ServletHandler.java:1166)
at Filters.FirstSiteFilter.doFilter(FirstSiteFilter.java:24)
at org.mortbay.jetty.servlet.ServletHandler$CachedChain.doFilter(ServletHandler.java:1157)
at org.mortbay.jetty.servlet.ServletHandler$CachedChain.doFilter(ServletHandler.java:1157)
at org.mortbay.jetty.servlet.ServletHandler$CachedChain.doFilter(ServletHandler.java:1157)
at org.mortbay.jetty.servlet.ServletHandler$CachedChain.doFilter(ServletHandler.java:1157)
at org.mortbay.jetty.servlet.ServletHandler.handle(ServletHandler.java:388)
at org.mortbay.jetty.security.SecurityHandler.handle(SecurityHandler.java:216)
at org.mortbay.jetty.servlet.SessionHandler.handle(SessionHandler.java:182)
at org.mortbay.jetty.handler.ContextHandler.handle(ContextHandler.java:765)
at org.mortbay.jetty.webapp.WebAppContext.handle(WebAppContext.java:418)
at org.mortbay.jetty.handler.HandlerWrapper.handle(HandlerWrapper.java:152)
at org.mortbay.jetty.Server.handle(Server.java:326)
at org.mortbay.jetty.HttpConnection.handleRequest(HttpConnection.java:542)
at org.mortbay.jetty.HttpConnection$RequestHandler.headerComplete(HttpConnection.java:923)
at org.mortbay.jetty.HttpConnection.handle(HttpConnection.java:404)
at com.google.tracing.TraceContext$TraceContextRunnable.runInContext(TraceContext.java:452)
at com.google.tracing.TraceContext$TraceContextRunnable$1.run(TraceContext.java:458)
at com.google.tracing.TraceContext.runInContext(TraceContext.java:698)
at com.google.tracing.TraceContext$AbstractTraceContextCallback.runInInheritedContextNoUnref(TraceContext.java:336)
at com.google.tracing.TraceContext$AbstractTraceContextCallback.runInInheritedContext(TraceContext.java:328)
at com.google.tracing.TraceContext$TraceContextRunnable.run(TraceContext.java:456)
at java.lang.Thread.run(Thread.java:679)
Caused by: java.io.IOException: Stream closed
at org.apache.jasper.runtime.JspWriterImpl.ensureOpen(JspWriterImpl.java:204)
at org.apache.jasper.runtime.JspWriterImpl.flushBuffer(JspWriterImpl.java:115)
at org.apache.jasper.runtime.PageContextImpl.release(PageContextImpl.java:188)
... 43 more

Logs suggest that exception occurs at Servlets.FW_FirstSite.doGet(FW_FirstSite.java:27) which is the statement rd.forward(request,response); and at Filters.FirstSiteFilter.doFilter(FirstSiteFilter.java:24) which is the statement chain.doFilter(request, response);.

Why do get these exceptions ?

Answer 1

My guess is that your call to response.getWriter() initiates writing the response to the client when it's being flushed. For that reason, you cannot anymore forward the request, as it has been already been flushed on.

You are allowed to set your response content type multiple times without it mattering, but you shouldn't call a writer unless you're already done with pre-processing.

Note also that calling getOutputStream() has the same effect.