Ok, alot of good suggestions, thanks! I will see if I can get customer feedback and analyze some of the things you mentioned.
Peter Crowther wrote: > > 2009/8/21 neilgoldsmith <ne...@avaya.com> > >> My first question, what is the best tool to monitor this so we can get an >> accurate description of when the problems occur and what might be at >> fault? >> They just started running perfmon (on a Windows system), but as of yet I >> have not seen any data from it. Is there a better monitoring tool? > > > For a first cut, there probably isn't. Perfmon will show you whether the > issue is CPU, RAM, disk or (theoretically) network; that then shows where > to > focus effort. If it's none of those... does your app use a database? > Might > there be contention to that database? Does the app use any internal > locking? Might there be contention for those locks? > > I would use some of the extra options in Perfmon after that first cut, > though. If you determine it's a CPU issue, for example, then gather CPU > statistics by process (it's under the Process object) and make sure it's > really Tomcat that's eating CPU. > > If you find that it's Tomcat eating CPU, or you find that there's no > obvious > bottleneck, then somebody needs to be standing by when the slowdown occurs > ready to take a thread dump on Tomcat. Try to get several: some under > normal operation, and as many as you can get, in sequence, when it's > running > slowly. Now look for differences! > > Also, you might want to enable garbage collection logging. Do the > slowdowns > correspond to periods when large objects (or large numbers of objects) are > allocated, and you're thus more likely to trigger a GC? If so, what JVM > are > you using, and what GC options? If it's a realtime application, you might > find one of the more realtime-optimised GCs helps - and you may find that > increasing thread counts and RAM make things no better and may actually > makes things worse, as GCs may take a little longer when they occur. > > >> Second question, what might we do to improve Tomcat performance? Should >> we >> continue to tweak the max threads and heap size? Any other Tomcat >> settings >> that we should look at that might directly relate to this server >> slowdown? >> > It's very hard to give more advice without the customer performing some of > the above steps, so that you've narrowed down the possible areas of > slowdown. It's a little too easy to tune something expecting it to make a > difference... and it does, the wrong way! > > Good luck! > > - Peter > > -- View this message in context: http://www.nabble.com/Tracking-down-a-Tomcat-slowdown-tp25081707p25084966.html Sent from the Tomcat - User mailing list archive at Nabble.com. --------------------------------------------------------------------- To unsubscribe, e-mail: users-unsubscr...@tomcat.apache.org For additional commands, e-mail: users-h...@tomcat.apache.org
