On Mon, Feb 14, 2011 at 7:32 AM, Rand <[email protected]> wrote: > JVM settings and how they relate to Railo/OpenBD/ACF. Which settings > affect which parts of the engine...
JVM tuning is a bit of a black art - and the best settings for your application running under your real world load are likely to be different to the best settings for my application running under my real world load. And, if your load changes - or your application changes in any substantial way - expect to have to re-tune the JVM. > i.e.: Making xmx and xms the same vs a range, also with perm size... > Also, I've seen options about telling the JVM WHICH garbage collector > to use, etc... To be honest, there's a LOT of information out there on JVM tuning but it's on the Sun/Oracle site (primarily) and other Java-focused sites. And that information applies regardless of which Java application you're running (in that you monitor/profile and load test, then tweak and repeat until you like the results). Different JEE servers are also part of the mix (because they are different applications and will have different memory footprints). At Macromedia, we used to run load tests and often tweak the JVM settings every time we launched a new application on the site. And we'd often run tweaking experiments on one server in the cluster to see if we could improve its performance (and then apply those changes across the cluster). We had a big document on everything we'd done and learned on the JVM for our internal applications - specific to our applications and configuration. As an example of something that may seem counter-intuitive and may or may not apply to your applications: sometimes you can get better performance by *lowering* the heap size. You will probably get more GC operations but you may well get fewer "stop the world" GCs. A lot depends on how many short-lived objects you cause the underlying Java system to create and what you do with them. But you'll only find out the optimum heap size by experimentation. -- Sean A Corfield -- (904) 302-SEAN Railo Technologies, Inc. -- http://getrailo.com/ An Architect's View -- http://corfield.org/ "If you're not annoying somebody, you're not really alive." -- Margaret Atwood -- tag/function ref: http://www.openbluedragon.org/manual/ mailing list - http://groups.google.com/group/openbd?hl=en Get to Texas in Feb for OpenCFSummit http://www.opencfsummit.org/
