I have a servlet that produce an excel file using POI HSSF. The info. printed 
on that file is obtained through a database.

The problem is that when I want to print a lot of rows on excel it throws an 
exception, as follows:

SEVERE: StandardWrapperValve[REPCBRR090SRV]: Servlet.service() for servlet REPCB
RR090SRV threw exception
java.lang.IllegalStateException: Cannot forward after response has been committe
d
        at org.apache.catalina.core.ApplicationDispatcher.doForward(ApplicationD
ispatcher.java:375)
        at org.apache.catalina.core.ApplicationDispatcher.access$000(Application
Dispatcher.java:123)
        at org.apache.catalina.core.ApplicationDispatcher$PrivilegedForward.run(
ApplicationDispatcher.java:138)
        at java.security.AccessController.doPrivileged(Native Method)
        at org.apache.catalina.core.ApplicationDispatcher.forward(ApplicationDis
patcher.java:355)
        at code.com.nextel.servlet.REPCBRR090SRV.doTask(REPCBRR090SRV.java:155)
        at code.com.nextel.servlet.NextelSrv.doGet(NextelSrv.java:77)
        at javax.servlet.http.HttpServlet.service(HttpServlet.java:740)
        at code.com.nextel.servlet.NextelSrv.service(NextelSrv.java:44)
        at javax.servlet.http.HttpServlet.service(HttpServlet.java:853)
        at org.apache.catalina.core.StandardWrapperValve.invokeServletService(St
andardWrapperValve.java:720)
        at org.apache.catalina.core.StandardWrapperValve.access$000(StandardWrap
perValve.java:118)
        at org.apache.catalina.core.StandardWrapperValve$1.run(StandardWrapperVa
lve.java:278)
        at java.security.AccessController.doPrivileged(Native Method)
        at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperV
alve.java:274)
        at org.apache.catalina.core.StandardPipeline.invoke(StandardPipeline.jav
a:505)
        at org.apache.catalina.core.StandardContextValve.invoke(StandardContextV
alve.java:212)
        at org.apache.catalina.core.StandardPipeline.invoke(StandardPipeline.jav
a:505)
        at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.j
ava:203)
        at org.apache.catalina.core.StandardPipeline.invoke(StandardPipeline.jav
a:505)
        at com.iplanet.ias.web.connector.nsapi.NSAPIProcessor.process(NSAPIProce
ssor.java:157)
        at com.iplanet.ias.web.WebContainer.service(WebContainer.java:598)

I have done several tests:

1. If I obtain 10K (10000 rows) from database, it produce an output on excel of 
around 25K rows. the difference is because all the titles and related stuff 
with the output (like titles, cuts, and so on just for printing purposes)
2. If I obtain 15K (15000 rows) from database, it produce an output on excel of 
around 30K rows.
3. Then  if I obtain 20K (20000 rows) from database, it produce an output on 
excel of around ????, here it throws the EXCEPTION!!!

I have increased my buffer size on the servlet with:
response.setBufferSize(32000);
when it had around 8900 (retrieved with getBufferSize()), and nothing.

Hope somebody can help me!

Thanks.
I appreciate you can reply me to: gab_s@hotmail.com