Thank you, Peter, I'll give it a look. %
--- Peter Lin <[EMAIL PROTECTED]> wrote: > > by the way, in case you haven't heard of it, > > http://mc4j.sourceforge.net/ > > mc4J can monitor tomcat4 and generate nice graphs. I > haven't used it, but it looks nice. > > peter > > > --- Michael Duffy <[EMAIL PROTECTED]> wrote: > > > > Hi Peter, > > > > Hiding in plain sight: > > > > > http://jakarta.apache.org/tomcat/articles/performance.pdf > > > > I apologize for overlooking it for all this time. > > I'll be sure to go through it right away. Thanks > - > > % > > > > > > --- Peter Lin <[EMAIL PROTECTED]> wrote: > > > > > > You might want to look at the VM performance > > numbers > > > in my Performance article. The link is listed on > > the > > > tomcat resources page. Generally, tweaking the > > > generations takes time. > > > > > > for something, like XML, tweaking generation > ratio > > > doesn't help. > > > > > > peter > > > > > > > > > Michael Duffy <[EMAIL PROTECTED]> wrote: > > > > > > Hi Yoav, > > > > > > > Yes to 1, and likely yes to 2. Check out the > > > > different garbage > > > > collector implementations, and the directives > > for > > > > setting old and young > > > > generation sizes. Your case is a classic one > for > > > > setting a small old > > > > generation size relative to the young > generation > > > > size: maybe even a 10-1 > > > > or slightly less ratio of young size to old > > size. > > > > > > I've never checked this page out before, but at > > your > > > prompting I found it today: > > > > > > http://java.sun.com/docs/hotspot/VMOptions.html > > > > > > I believe the docs are telling me that the > default > > > value of XX:NewRatio=12 for Intel. Is that > > correct? > > > If that's true, should I just leave the default? > > > > > > I have no experience with setting any of these > > > values. > > > I've always used the JVM right out of the box > (my > > > ignorance). > > > > > > What would be a minimum set of parameters to > span > > > this > > > space? Thanks - % > > > > > > > > > --- "Shapira, Yoav" wrote: > > > > > > > > Hi, > > > > > > > > >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 > > > > > > > > It's not a good idea to set -Xmx to a higher > > > amount > > > > than the amount of > > > > physical RAM: the JVM will thrash once it > > reaches > > > > much less than 512MB. > > > > > > > > >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. > > > > > > > > Your understanding is good and correct on the > > > above > > > > issues. > > > > > > > > >(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? > > > > > > > > Yes to 1, and likely yes to 2. Check out the > > > > different garbage > > > > collector implementations, and the directives > > for > > > > setting old and young > > > > generation sizes. Your case is a classic one > for > > > > setting a small old > > > > generation size relative to the young > generation > > > > size: maybe even a 10-1 > > > > or slightly less ratio of young size to old > > size. > > > > > > > > And there's the ever-present (which is why > it's > > > > often forgotten) advice: > > > > you might want to get more physical RAM. It's > > > > pretty cheap, and 512MB > > > > isn't that much for a server nowadays. > > > > > > > > Yoav > > > > > > > > > > > > > > > > This e-mail, including any attachments, is a > > > > confidential business communication, and may > > > contain > > > > information that is confidential, proprietary > > > and/or > > > > privileged. This e-mail is intended only for > the > > > > individual(s) to whom it is addressed, and may > > not > > > > be saved, copied, printed, disclosed or used > by > > > > anyone else. 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