Why does the Sun JVM continue to consume ever more RSS memory even when the heap, etc sizes are stable?

Question

Over the past year I\'ve made huge improvements in my application\'s Java heap usage--a solid 66% reduction. In pursuit of that, I\'ve been monitoring various metrics, such

Answer 1

The current garbage collector in Java is well known for not releasing allocated memory, although the memory is not required anymore. It's quite strange however, that your RSS size increases to >3GB although your heap size is limited to 640MB. Are you using any native code in your application or are you having the native performance optimization pack for Tomcat enabled? In that case, you may of course have a native memory leak in your code or in Tomcat.

With Java 6u14, Sun introduced the new "Garbage-First" garbage collector, which is able to release memory back to the operating system if it's not required anymore. It's still categorized as experimental and not enabled by default, but if it is a feasible option for you, I would try to upgrade to the newest Java 6 release and enable the new garbage collector with the command line arguments "-XX:+UnlockExperimentalVMOptions -XX:+UseG1GC". It might solve your problem.