Hi,

I am running a system which consists of eight concurrent Java processes. All these processes run on the same box and are backend daemon processes which means they are designed to be started and then run continuously, as they are backend processes they have no user interface. Thus the processes are controlled (paused/shutdown etc...) by parameters in a database they interact with (also on the same box). The system has more than enough CPU power to run these processes (and then some). However the problem is the amount of memory they consume. The spec of the box/environment is below:

Sun Sparc v9 1.3Ghz CPU (x2) with 4 Gig of RAM (1.2 Gig available) - Running Solaris 9 (SunOS 5.9)
Oracle 10g (10.1.0.4.0) (This is way only 1.2 Gig of RAM is available)
Sun Solaris Mixed Mode JRE 1.5.0.03

I have configured the eight current Java processes through JVM options to run within the 1.2 Gig of available RAM. Thought the system is on the limit only having around 100-200 free Megs of RAM and a portion of each JVM has to be swapped out of RAM to disk. This situation is fine for the time being as the swapped out portions are idle code/data for the most part. Each JVM consumes around 160-180 Megs of RAM.

An example of the options I am passing to the JVM are below:

-server -d64

-Djava.awt.headless=true

-Xms16384k
-Xmx16384k

-XX:NewSize=12288k
-XX:MaxNewSize=12288k
-XX:NewRatio=128
-XX:TargetSurvivorRatio=90
-XX:MinHeapFreeRatio=5
-XX:MaxHeapFreeRatio=85

-XX:+UseParallelGC
-XXarallelGCThreads=2
-XX:+UseAdaptiveSizePolicy
-XX:MaxTenuringThreshold=32

-XXermSize=4096k
-XX:MaxPermSize=4096k

-XX:ThreadStackSize=512

-XX:CompileThreshold=16384

-Xconcurrentio

The real problem is that now an additional three daemon Java processes need to be run on this box. To do this will require around another 600 Megs of RAM. Thought the system only has 100-200 free. I requested more memory for the box, but who knows how long that will take!

Oracle's SGA (System Global Area - its memory footprint) has already been reduced to a minimum and moving the Java processes to another box is feasible but deemed not viable as there is no other production systems with available resources to take the load (CPU wise).

So I am hoping that somebody out there knows of any tips or tricks to get these JVM processes running in less RAM.

I don't want to reduce the heap sizes any more than I already have. Garbage collections are frequent enough already with such a small heap, the only reason this situation is acceptable is due to the CPU performance of the system.

Any suggestions?

I hope Sun release the MVM (Multi-Tasking Virtual Machine) for JRE 1.5 soon, as I know I am not the only one battling with this situation.