Peter, Do you have more specifics on this? "...TC5 has the new status servlet, which will tell you how much heap is actually in use currently."
I've been using the /manager and jmxpoxy app URL's but I can't find anything which has heap info in it. What am I missing? /manager/list /manager/serverinfo /manager/jmxproxy etc. http://jakarta.apache.org/tomcat/tomcat-5.0-doc/manager-howto.html Thanks, -Dave -----Original Message----- From: Peter Lin [mailto:[EMAIL PROTECTED] Sent: Wednesday, June 09, 2004 8:12 AM To: Tomcat Users List Subject: Re: Memory Settings On Tomcat if you can upgrade to tomcat5, I would recommend it. the reason I suggest this is TC5 has the new status servlet, which will tell you how much heap is actually in use currently. the JVM will not release memory back to the OS that is true. in terms of performance the biggest indicator of poor performance is the rate at which the heap grows and the frequency of full GC. Applications that are well behaved should result in regular intervals of full GC. Poor performing applications wiill cause erratic and frequent full GC. Even if you can't upgrade to TC5, it might be worth it to d/l and install it. Once you have it installed, you can use JMeter to view the server load and the memory usage pattern. I hope that helps. peter Michael Duffy <[EMAIL PROTECTED]> wrote:I recently had a problem with a Windoze server hanging up due to memory problems. I've got Tomcat 4.1.29 installed to run as a service under JDK 1.4.1_05 on this Windows 2000 server. The Tomcat memory settings on startup are -Xms64m and -Xmx1024m. The server has 512MB of physical RAM installed. The Windoze task manager says Tomcat is sitting at ~128MB of memory. My understanding is that Java's garbage collection will reclaim heap-allocated memory to the JVM, but not necessarily to the OS. Is this true? What this means is that a Windoze server admin could look at the task manager and see a large memory usage for Tomcat, but that doesn't necessarily reflect Tomcat's current usage. It's more like a high water mark on a pier: it'll show the highest value that Tomcat has used, but the real value will be lower if the garbage collector runs and the tide goes out. If you read a lot of objects into session you could end up with a big high water mark. The application is a JSP front end with a single controller servlet that interacts with an Oracle database. The only data members in the servlet are some read-only map that are initialized on startup. There are some session data that are maintained for certain user requests, but the rest are all stateless request/response. The server admin is saying that the problem is Windoze memory management. When a new process starts up outside of Tomcat, it could be that memory isn't reachable, and the new process hangs. We're going to increase the virtual page size on Windoze and change the startup settings for the Tomcat service to -Xms256m and -Xmx1536m. So my questions are: (1) Is my understanding of the interaction between the JVM and OS memory management correct? (2) Are there any other tuning settings for Tomcat that I need to look at? Thanks - % __________________________________ Do you Yahoo!? Friends. Fun. Try the all-new Yahoo! Messenger. http://messenger.yahoo.com/ --------------------------------------------------------------------- To unsubscribe, e-mail: [EMAIL PROTECTED] For additional commands, e-mail: [EMAIL PROTECTED] --------------------------------- Do you Yahoo!? Friends. Fun. Try the all-new Yahoo! Messenger --------------------------------------------------------------------- To unsubscribe, e-mail: [EMAIL PROTECTED] For additional commands, e-mail: [EMAIL PROTECTED]
