Thanks Charles. I found that later in a link I got from Google. I'd found lots of references to how to set MaxPermGen, but I already knew that. I also found lots of references that the default was 64Mb, which didn't jive with the 86Mb that one instance had. Perhaps the 64bit server default is a good bit higher than the 32bit version. Plus I was reading it, erroneously, as the starting value. I think I'll stick to searching the SUN docs on this stuff like I used to. I googled thinking it would probably get me to some Sun docs quickly, but it's returning a lot of other links.
Yea, if I'm really worried about it, I watch it with jconsole. I had just found it interesting on reviewing the thread dumps - it looked odd. Yes, the two loads are vastly different, different # users, different dataset sizes, different usage patterns. From my support folks, I hear that instance 1 has probably been lightly used the last 2 days, but will probably be having more usage today/tomorrow - and heavy data pulls at that. The numbers will probably be vastly different at the end of the day tomorrow. Thanks again. -----Original Message----- From: Caldarale, Charles R [mailto:chuck.caldar...@unisys.com] Sent: Wednesday, January 20, 2010 1:08 PM To: Tomcat Users List Subject: RE: PermGen question > From: Jeffrey Janner [mailto:jeffrey.jan...@polydyne.com] > Subject: PermGen question > > Instance 1: > PSPermGen total 43712K, used 43613K [0x000000007fff0000, > 0x0000000082aa0000, 0x00000000853f0000) > object space 43712K, 99% used > [0x000000007fff0000,0x0000000082a875d8,0x0000000082aa0000) > > Instance 2: > PSPermGen total 86016K, used 45979K [0x000000007fff0000, > 0x00000000853f0000, 0x00000000853f0000) > object space 86016K, 53% used > [0x000000007fff0000,0x0000000082cd6ef8,0x00000000853f0000) > Obviously, I'm concerned about that 99% used value in the first > instance, and will be going back to address it. It is likely not a problem. That's 99% used of what's allocated, not the maximum - 99% is a good thing (high efficiency). I'd be more concerned about Instance 2, where PermGen expanded to 86MB at one point. > However, I would have thought that it would have the same > size as instance 2. Unless they have identical workloads with identical requests, there will be variance. > Can someone explain what's happening here that I'm not seeing? Nothing unusual is going on. > I didn't think that the PermGen grew or shrunk over time. You thought wrong. There are parameters for both initial and maximum PermGen size; unless they're explicitly set to the same value, PermGen will expand and contract, just like the Java heap. It's often more illuminating to use JConsole or JVisualVM to monitor heap and PermGen usage over a significant time period, rather than looking at snapshots. - 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 ******************************* NOTICE ********************************* This message is intended for the use of the individual or entity to which it is addressed and may contain information that is privileged, confidential, and exempt from disclosure under applicable law. If the reader of this message is not the intended recipient or the employee or agent responsible for delivering this message to the intended recipient, you are hereby notified that any dissemination, distribution, or copying of this communication is strictly prohibited. If you have received this communication in error, please notify us immediately by reply or by telephone (call us collect at 512-343-9100) and immediately delete this message and all its attachments. --------------------------------------------------------------------- To unsubscribe, e-mail: users-unsubscr...@tomcat.apache.org For additional commands, e-mail: users-h...@tomcat.apache.org
