This sounds like a threading issue in you app. POI may be making the problem more visible because it sounds like its taking some time to complete.
-Ryan ----- Original Message ----- From: <[EMAIL PROTECTED]> To: <[EMAIL PROTECTED]> Sent: Friday, January 09, 2004 9:41 AM Subject: RE: Locking up Application Server when creating new HSSFWorkbook > We have tried most of the suggestions provided without luck (and thanks for > the responses). Garbage collection appears to be functioning fine. CPU > utilization remains low. As we have been testing this more, one interesting > thing that we have found is that other user requests to the server will > eventually be processed while the HSSFWorkbook is being instantiated but not > in a timely manner. In other words, if I open 2 browsers and start the part > that uses POI the application will appear to hang to the second browser. > But a request made by the 2nd browser while the app seems to be hung will > eventually come back before the POI piece completes in the first browser. > > More info on our environment - 1 WAS 5.0.1 running on Linux, JRE 1.3.1. > > -----Original Message----- > From: Michael Zalewski <[EMAIL PROTECTED] > <mailto:[EMAIL PROTECTED]> >@MOORECORP > Sent: Wednesday, January 07, 2004 7:44 PM > To: Klein, Pat (WTC/Lisle) > Subject: RE: Locking up Application Server when creating new HSSFWorkbook > > > If the Admin Console also hangs up, that is a sign that something else is > going on. The Admin server runs in a separate JVM, so it won't be as > severely impacted by garbage collection on your web application. The Admin > Console still runs, even if a Web Application Server is entirely locked up. > However, a large amount of garbage collection may slow the admin console > down to a crawl, because of 100% CPU utilization, especially under Windows > single processor systems. > > Is your server running on Windows? And are there multiple processors? > Another possibility might be that requests fail to get processed because of > network I/O. Garbage collection might cause worse lockups of the admin > console if only a single processor. > > What version of Websphere? Probably 4.0? If 5.0 or 5.1, you might consider > acoliver's suggestion of using a newer JRE for your web application. If you > are using 4.0, you can use only JRE up to 1.3 I believe. But parallel > garbage collection will not help much if your admin console (separate JVM) > is also locking up. > > When you turn performance monitoring on, look to see if there are *several* > garbage collection sweeps made in between the instantiation of HSSFWorkbook > and the next line. (I assume you are reading a large workbook - This is > exactly the problem case for POI on a web server environment). > > -----Original Message----- > From: [EMAIL PROTECTED] <mailto:[EMAIL PROTECTED]> > [mailto:[EMAIL PROTECTED] > <mailto:[mailto:[EMAIL PROTECTED]> > Sent: Wednesday, January 07, 2004 9:04 AM > To: [EMAIL PROTECTED] <mailto:[EMAIL PROTECTED]> > Subject: RE: Locking up Application Server when creating new HSSFWorkbook > > Thanks for the response. When the server hangs,everythingrunning on > Websphere hangs- adminconsole and all. We have been able to trace the > moment of hang up to the instantiation of the HSSFWorkbook. > We are currently using the internal HTTP server andlockups can be duplicated > everytime we run a large excel file. I will try turning on the tracing and > see what I see. > Thanks... > -----Original Message----- > From: Michael Zalewski <[EMAIL PROTECTED] > <mailto:[EMAIL PROTECTED]> >@MOORECORP > Sent: Tuesday, January 06, 2004 7:12 PM > To: POI Users List > Subject: RE: Locking up Application Server when creating new HSSFWorkbook > I have also had similar problems (Websphere 4.0). I think in my case it was > because of an excessive number of objects being created and destroyed (i.e., > garbage collection tool several seconds). But I never fully diagnosed the > problem (And I am not even sure that the problem was due to POI). > I don't know what you mean when you say 'Websphere app server hangs up'. Do > you mean that there is no response from the admin console? No response from > any servlet? Or just no response from the servlet that creates a > HSSFWorkbook? Do you have a load balanced environment? Could session > serialization be a problem? (Are you putting the HSSFWorkbook into a > HttpSession, and letting Websphere try to persist the session?) Are you > trying to send a large spreadsheet to the client with https? > You could try the following: > 1) Use Websphere's own internal HTTP Server, instead of Apache/IIS/Netscape > 2) Lower the amount of heap memory used. See if that makes the lockups more > frequent. > 3) Turn on Garbage Collection tracing. See if generating the HSSFWorkbook > causes many sweeps. > I think that Garbage Collection is the most likely culprit. (A JVM can do > very little while a garbage collection is in process. That would cause your > application to freeze. But the Admin Console and other application servers > should continue to respond). > If the problem is limited to a single servlet, you might also be > synchronizing the servlet object on the request. For example, if there is a > servlet that implements SingleThreadModel, (or if you set it up that way in > web.xml), then subsequent requests for workbooks will appear to freeze until > the first workbook is completely downloaded. > -----Original Message----- > From: [EMAIL PROTECTED] <mailto:[EMAIL PROTECTED]> > [mailto:[EMAIL PROTECTED] > <mailto:[mailto:[EMAIL PROTECTED]> > Sent: Tuesday, January 06, 2004 11:26 AM > To: [EMAIL PROTECTED] <mailto:[EMAIL PROTECTED]> > Subject: Locking up Application Server when creating new HSSFWorkbook > We are running into a strange issue on our application. When we are > reading in an existing Excel spreadsheet (about 3.5 MB) and creating a > new HSSFWorkbook, our entire WebSphere app server hangs up. Once the > workbook is created, all is well again. As far as we can tell, there > are plenty of system resources available (CPU and memory). The POI > version that we are using is 2.0 RC1. > > Anyone run into a similar problem? > > Thanks in advance... > --------------------------------------------------------------------- > To unsubscribe, e-mail: [EMAIL PROTECTED] > <mailto:[EMAIL PROTECTED]> > For additional commands, e-mail: [EMAIL PROTECTED] > <mailto:[EMAIL PROTECTED]> > --------------------------------------------------------------------- To unsubscribe, e-mail: [EMAIL PROTECTED] For additional commands, e-mail: [EMAIL PROTECTED]
