Java HotSpot Virtual Machine

Hiya,

I've been having some performance issues with my java application and I have figured out what is happening but I am not sure on the best approach to resolve it.

Basically, the application caches a lot of web pages and content - so when this happens it gets put into the old generation space, as more and more people visit the website more and more content is cached, and because the garbage collector cannot free much memory during a full garbage collection it spams FGC's until the tomcat server crashes.

This leads me to think that there are two possible solutions ...

1) Increase the size of the heap and give the old generation more space to play with.
2) Decrease the amount that the jahia application caches.

The problem with the first option is that I have just upgraded my heap size from 2GB to 2.5GB, but it didnt affect the size of the old generation as you can see below. Is there a way i can specify more on the old generation? and what should the new generation be in relation to the old?

The second option is less of a java specific option, and something I will need to look into.

So to sum up, my questions are :-

1) What should the old generation and new generation ratio be?
2) How can I set the size of the old generation and the new generation?

Heap Configuration:
MinHeapFreeRatio = 40
MaxHeapFreeRatio = 70
MaxHeapSize = 2621440000 (2500.0MB) <<<< New HEAP is 2.5G
NewSize = 655360 (0.625MB)
MaxNewSize = 4294901760 (4095.9375MB)
OldSize = 1441792 (1.375MB)
NewRatio = 8
SurvivorRatio = 8
PermSize = 16777216 (16.0MB)
MaxPermSize = 134217728 (128.0MB)

Eden Space:
capacity = 239271936 (228.1875MB)
used = 215276592 (205.3037567138672MB)
free = 23995344 (22.883743286132812MB)
89.97151759577855% used

PS Old Generation
capacity = 1908932608 (1820.5MB) <<<<<<<<<<<<< Still set to 1.8GB
used = 1604151664 (1529.8382415771484MB)
free = 304780944 (290.66175842285156MB)
84.03395998775878% used