Chuck, So are you saying it will reduce the upper consumed heap? I have -Xms = -Xmx, so maybe that's why I never see a reduction. Our core load is from 9am - 7pm CST, and we have virtually nothing from 11pm to 5am. So if low heap usage should ever cause the JVM to drop the consumed heap, that is when it would, but it has never happened.
Like I said before, though, it gets to about 15% of max memory available and seems to run just fine there. -----Original Message----- From: Caldarale, Charles R [mailto:chuck.caldar...@unisys.com] Sent: Tuesday, February 08, 2011 12:53 PM To: Tomcat Users List Subject: RE: Is IBM Right About Java? > From: Robinson, Eric [mailto:eric.robin...@psmnv.com] > Subject: RE: Is IBM Right About Java? > As I understand it, it would actually not work because instances that > peak at 512M but then go back down to, say, 128M, would still never > return the unused memory to the OS so it can be used by other instances. Not true - that's the whole point of the -Xms setting. If GC can squeeze the heap down, it will do so and avoid allocations in the now unused virtual space. There are some heuristics in place within GC to avoid bouncing up and down, so heap usage has to stay low for a while before you'll see a lower upper limit and a corresponding reduction in the real memory usage. (Note that the unused virtual space may not be returned to the OS, but the real space behind it won't be referenced so the pages will age out - but only if the OS needs the space for some other process.) - 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 --------------------------------------------------------------------- To unsubscribe, e-mail: users-unsubscr...@tomcat.apache.org For additional commands, e-mail: users-h...@tomcat.apache.org
