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. If you are not the(an) intended > > recipient, please immediately delete this e-mail > > from your computer system and notify the sender. > > Thank you. > > > > > > > --------------------------------------------------------------------- > > To unsubscribe, e-mail: > > [EMAIL PROTECTED] > > For additional commands, e-mail: > > [EMAIL PROTECTED] > > > > > __________________________________________________ > Do You Yahoo!? > Tired of spam? Yahoo! Mail has the best spam > protection around > http://mail.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 __________________________________ 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]
