High Eden Java Memory Usage/Garbage Collection

Hi,

I am trying to make sure that my Coldfusion Server is optomised to the max and to find out what is normal limits.

Basically it looks like at times my servers can run slow but it is possible that this is caused by a very old bloated code base.

Jrun can sometimes have very high CPU usage so I purchased Fusion Reactor to see what is going on under the hood.

Here are my current Java settings (running v6u24):

java.args=-server -Xmx4096m -Xms4096m -XX:MaxPermSize=256m -XX:PermSize=256m -Dsun.rmi.dgc.client.gcInterval=600000 -Dsun.rmi.dgc.server.gcInterval=600000 -Dsun.io.useCanonCaches=false -XX:+UseParallelGC -Xbatch ........

With regards Memory, the only memory that seems to be running a lot of Garbage Collection is the Eden Memory Space. It climbs to nearly 1.2GB in total just under every minute at which time it looks like GC kicks in and the usage drops to about 100MB.

Survivor memory grows to about 80-100MB over the space of 10 minutes but drops to 0 after the scheduled full GC runs. Old Gen memory fluctuates between 225MB and 350MB with small steps (~50MB) up or down when full GC runs every 10 minutes.

I had the heap set to 2GB initally in total giving about 600MB to the Eden Space. When I looked at the graphs from Fusion Reactor I could see that there was (minor) Garbage Collection about 2-3 times a minute when the memory usage maxed out the entire 600MB which seemed a high frequency to my untrained eye. I then upped the memory to 4GB in total (~1.2GB auto given to Eden space) to see the difference and saw that GC happened 1-2 times per minute.

Is it normal in Coldfusion that the Eden memory would grow so quickly and have garbage collection run so often? i.e do these graphs look normal?

Also should I somehow redistribute the memory available to give the Eden memory more since it seems to be where all the action is?

Any other advice for performance improvements would be much appreciated.

Note: These graphs are not from a period where jrun had high CPU.

Here are the graphs:

PS Eden Space Graph