Have you tuned your JVM on ColdFusion MX yet?

September 25, 2002
coldfusionjava

ColdFusion's move to java gives developers and system administrators a wealth of performance tuning options. This is due to the fact that the runtime for ColdFusion is now pluggable (the JVM), we don't have to rely completly on Macromedia to make performance optomizations, we can use different JVM's and lots of different JVM settings to improve the performance and scalibility of our ColdFusion Applications. This is a topic I haven't seen much discussion about yet, and I'm not sure why.

What JVM should I use?

You have lots of choices, IBM, Sun and BEA all make JVM's, each will perform differently. Which is the fastest? I couldn't tell you, it will depend on your server platform, and your application. Sun being the creator of Java, has the most popular JVM, but if you are really concerned about performance you should test with each vendor's JVM.
Here are some articles that may help make your decision (in no particular order)

Tuning Your JVM There are lots of things you can do to tune the JVM, typically there are memory settings, threading settings, and garbage collection settings. For memory settings make sure you Max heap is big enough, also set the initial heap size to be equal to the max heap size, this way all memory is allocate when the server starts up, rather than when it needs it (during a request, allocating memory is slow). Look for a file called Xusage that comes with your JVM this usually shows some of the options that you can set, also look in your JVM docs for more info. You can tune these settings just like you tune your web server or other web applications. Sun Performance tuning links

I haven't had the time to do any JVM testing on ColdFusion MX yet, but if you have I'd love to hear about your experiences email me pete@cfdev.com.



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Comments

Pete, Your links here are pretty helpful. I just recently went to new york to help a client solve problems related to the dreaded Java.lang.OutOfMemory error which is in large part to lack of good degault settings in the Jrun.xml for the scheduler (and somewhat for the proxy) service. Alot of people who are getting these errors mistakenly think its only a JVM issue but its a jrun.xml settings issue but tuning the JVM can really increase performance, reduce the out of memory errors and in general make more people happy. Some time this weekend Ill blog all my results as well as my general rules and ideas on JVM tuning for CFMX.
Here is a link to that blog entry http://www.robisen.com/index.cfm?mode=entry&entry=FD4BE2FC-55DC-F2B1-FED0717CC1C7E0AF
I am having several issues that appear as you stated Robi. They are JVM errors as the logs state, relating to memory. I was interested in reading your blog, but the link isn't working for me. Hopefully you will get this message so I may be enlightened. I'm running the latest 6.1 package of CFMX, and this thing kills a server at least 4 times a day now. Any help would be appreciated. I may start testing a new jvm if you don't get this! P
BTW, I'm a different Pete.. Should have stated so! Insightful article Pete #1. Thanks
Found the article very useful, I also had a peek at the article on peak code optimisation principles, Amanada Peet. Pete#2 you may find that interesting...
Good information! I am looking to dig into CFMX threads, so that I can see specific code executing. I know that we can issue dumps of a stack trace; however, I am looking for something a bit more easy to implement in a production environment. It seems to me, that I should be able to see CFMX programs run in real time. I can see the individual threads, but not the underlying code that is executing. We are running CFMX 6.1 and have been for almost four years without any problems at all. However, lately we see high CPU usage with threads stacking up. We can communicate with all Databases, but the threads still stack during peak load time. Any thoughts on a tool or existing Java methods I can use to acquire more information?

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