I've got a really odd situation that I'm not understanding. I figured the gurus could explain it to me.
I have two Tomcat instances deployed as services on the same 64bit Windows 2008 machine with Sun JDK 1.6.0_13 64bit. They are running the same apps but for different user bases and were deployed per the Tomcat doc on running multiple instances. The only difference in their configs, besides the obvious file pointers, is the memory settings. Instance 1 is -Xmx=5000M -Xms5000M Instance 2 is -Xmx=4096M -Xms3092M (yes, I know, it's best to make them the same) Neither has a Thread Stack Size set. When I did a thread dump on each instance, I noticed that the PermGen space for each instance was different. Even more interesting, the instance with the smaller memory settings had the larger PermGen. Instance 1: Heap PSYoungGen total 1622976K, used 714557K [0x0000000155950000, 0x00000001bdbf0000, 0x00000001bdbf0000) eden space 1534528K, 44% used [0x0000000155950000,0x000000017f3795b0,0x00000001b33e0000) from space 88448K, 36% used [0x00000001b8590000,0x00000001ba536148,0x00000001bdbf0000) to space 83648K, 0% used [0x00000001b33e0000,0x00000001b33e0000,0x00000001b8590000) PSOldGen total 3413376K, used 867706K [0x00000000853f0000, 0x0000000155950000, 0x0000000155950000) object space 3413376K, 25% used [0x00000000853f0000,0x00000000ba34ead0,0x0000000155950000) PSPermGen total 43712K, used 43613K [0x000000007fff0000, 0x0000000082aa0000, 0x00000000853f0000) object space 43712K, 99% used [0x000000007fff0000,0x0000000082a875d8,0x0000000082aa0000) Instance 2: Heap PSYoungGen total 989312K, used 149224K [0x000000012fea0000, 0x000000016fea0000, 0x00000001853f0000) eden space 932544K, 15% used [0x000000012fea0000,0x0000000138c55de0,0x0000000168d50000) from space 56768K, 7% used [0x0000000168d50000,0x0000000169154480,0x000000016c4c0000) to space 54400K, 0% used [0x000000016c980000,0x000000016c980000,0x000000016fea0000) PSOldGen total 2097152K, used 174926K [0x00000000853f0000, 0x00000001053f0000, 0x000000012fea0000) object space 2097152K, 8% used [0x00000000853f0000,0x000000008fec3a20,0x00000001053f0000) 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. However, I would have thought that it would have the same size as instance 2. Can someone explain what's happening here that I'm not seeing? I didn't think that the PermGen grew or shrunk over time. Other than the heap size differences, the only other thing that's different is that #1 has been running a day or two longer than #2. ================================================================= Jeffrey W. Janner e-mail: jeffrey.jan...@polydyne.com <mailto:jeffrey.jan...@polydyne.com> PolyDyne Software Inc. web: http://www.polydyne.com/ <http://www.polydyne.com/> 9390 Research Blvd. phone: (512) 343-9100 x8930 Building 1, Suite 400 fax: (512) 343-9297 Austin, TX 78759 ================================================================= ******************************* 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.
