Also remember to statically size heap regions manually if you can as that will always improve GC performance and as for heap sizing keep the heap sized to reduce GC time to less than 1% of the time especially on servers with more than 8 cores. Also if the application is a web app with any kind of response time requirements I would strongly suggest that you use
-XX:+UseConcMarkSweepGC -XX:+UseParNewGC -XX:+UseCMSInitiatingOccupancyOnly -XX:CMSInitiatingOccupancyFraction=85 this will keep the app server from having an long pauses that can be detected by users how tend to refresh if current experience is more than 4X normal which can cause extra artificial load. -----Original Message----- From: Caldarale, Charles R [mailto:chuck.caldar...@unisys.com] Sent: Tuesday, March 10, 2009 9:57 AM To: Tomcat Users List Subject: RE: Effect of Heap Size on Performance? > From: Christopher Schultz [mailto:ch...@christopherschultz.net] > Subject: Re: Effect of Heap Size on Performance? > > A smaller heap means that you'll catch even small memory leaks faster. Good for debugging, but provokes more frequent GCs, so may not be optimal for production. I tend to use the largest heap that will avoid paging; this is often difficult to determine, unless the system you're running on is used only for the one Java application. > Granted, a larger heap invites more objects into it The above requires clarification: the max size of the heap has nothing to do with the number of persistent objects the application creates - that's purely a function of the app; the number of dead (unreachable) objects has negligible effect on GC time. - Chuck THIS COMMUNICATION MAY CONTAIN CONFIDENTIAL AND/OR OTHERWISE PROPRIETARY MATERIAL and is thus for use only by the intended recipient. If you received this in error, please contact the sender and delete the e-mail and its attachments from all computers. --------------------------------------------------------------------- To unsubscribe, e-mail: users-unsubscr...@tomcat.apache.org For additional commands, e-mail: users-h...@tomcat.apache.org This e-mail may contain Sprint Nextel Company proprietary information intended for the sole use of the recipient(s). Any use by others is prohibited. If you are not the intended recipient, please contact the sender and delete all copies of the message. --------------------------------------------------------------------- To unsubscribe, e-mail: users-unsubscr...@tomcat.apache.org For additional commands, e-mail: users-h...@tomcat.apache.org
