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Back to newsletter 138 contents
Included in the list of goodies I mentioned in last month's newsletter that are now available in Java7 u4 were GC notifications, and this month I've written an article showing how they are accessed. Pop over to fasterj.com and adapt the code for your application so that your GC monitoring is state-of-the-art.
Also, I promised to get back to you about the initial JVM heap size - a question I asked you two newsletters ago. Your replies were very useful and interesting. First off a number of you pointed out that some JVMs had no initial heap size to even specify (e.g. Excelsior Jet and Azul Zing). Then, for those JVMs that do specify initial heap size, the JVM specifics and the garbage collector in use mattered. A few of you had actually varied the initial heap when you tuned your systems and were able to tell me that: The Oracle JVM on some systems with some garbage collectors showed worse performance with initial set to maximum heap; whereas the IBM JVM on some systems showed better performance with initial set to maximum heap.
It's worth pointing out that any performance gain or loss from this is going to be very small, and several of you just set initial to maximum to make configuration simpler (one less thing to worry about) - if performance is adequate, I guess this is not unreasonable.
The summary for me is that I've learned there is still no optimal choice for the initial heap size - you need to test it for your choice of JVM and garbage collector, along with any other tunable options, and see what's best for your application. Not the clarity of result I'd like, but not really surprising.
Finally, I'm going to mention Madhu Konda and his recently published book "Just Spring Integration" not because it is relevant to Java performance, but because we had a chat about it after out of the blue Madhu stopped me in the street having recognised me! Any other Java authors who randomly stop me in the street for a chat will similarly get a mention in future :-)
Now on to all our usual links to Java performance tools, news, articles. We've got that article on Garbage Collection JMX Notifications and, as ever, all the extracted tips from all of this month's referenced articles.
Java performance tuning related news.
Java performance tuning related tools.
Back to newsletter 138 contents
