Listers, I thought a quick note on 64bit JVMs would be helpful. At present, using a 64bit VM is almost always the wrong thing to do. While it allows you to allocate more than 2Gb in heap size (memory), the downside is that you may experience performance delays as the Java garbage collector "kicks in" and removes unused objects from the heap. Naturally, the bigger the heap, the longer this process will take.
Often, a better solution is to run multiple JVMs - ie multiple copies of Tomcat - and distribute the load. Not only does this mean you gain resilience, but you can allocate smaller heaps and hence reduce the chances of a delay as the garbage collector is invoked. Many enterprises that specialise in hosting mission critical Java applications (I could name two global investment banks off the top of my head) will encourage this deployment strategy over one JVM with a massive heap. I am led to believe there's a new GC available in the next release of Java (http://www.javabeat.net/tips/200-g1-garbage-collector-in-java-70.html) but even then, one has to ask the question, wouldn't it be better to run multiple JVMs ideally in different datacentres, to ensure a consistently good level of performance with improved resilience? John Baker -- Single Sign On for the AR system http://www.javasystemsolutions.com/jss/ssoplugin _______________________________________________________________________________ UNSUBSCRIBE or access ARSlist Archives at www.arslist.org attend wwrug11 www.wwrug.com ARSList: "Where the Answers Are"
