I reckon this still might be a garbage collection problem. I would download jvmstat from sun and use visualgc to monitor this. It gives a good graphical representation of when the box is garbage collecting and how much stuff is in each of the generations.
We had a similar situation and this arose because the app created lots of very short lived objects. Increasing the young generation size alleviated this problem and also reducing tenuring so medium term objects made it to the old generation. There are also a few more garbage collection parameters you can play with. If you have multiple processors you could try enabling the parallel collector. There is also the Concurrent Mark Sweep collector which locks the JVM only in a small part of it's collection. You could try using the aggressive heap settings which will try to use all the memory in the machine that it can. I think more visibility of your garbage collection cycles is the first port of call in any event. -----Original Message----- From: Sam Gallant [mailto:[EMAIL PROTECTED] Sent: 14 October 2004 20:17 To: [EMAIL PROTECTED] Subject: Tomcat 5 pause (free gmail account for fix :-) Everyone, Thanks in advance for any help. Also I have a gmail invite for the person who has a fix for this if they are interested. My company has been using Tomcat for several years, but a problem has crept up that we have not been able to solve. Basically, tomcat will stop processing requests for 2-60 second period several times a day. Here is a list of software that we have tried. (Note we have tried changing each key componant to see if we isolate the componant that is the problem, but no luck yet) OS: RedHat 9 & AS3 Threading model: linux threads & nptl JVM: sun 1.4.2_4 & latest ibm Http connector: ajp w/apache 2 and coyote connector JBDC connector 1.0 1. Doesn't always happen durning old gen garbage collection, but does sometimes 2. Before switching to incremental gc we received out of memory errors which resulted in Tomcat completly hanging 3. After switching to incremental gc the effect changed to 2-60 second periods of time that Tomcat won't process request, but it does resume on its' own. 4. Cpu usage for most of the day is less than 20% utiliztion, but when the problem occurs the cpu spikes to 100% utiliztion briefly. --------------------------------------------------------------------- To unsubscribe, e-mail: [EMAIL PROTECTED] For additional commands, e-mail: [EMAIL PROTECTED]
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