Recommended memory settings for the deployment of HTB in the JVM?

Hi Gaetan,

I do not remember having seen any recommendations from Oracle on this, except for some hints in their HTB V5 benchmark.

We have done some testing on this and the settings we have found to give the most throughput are:

-server -XX:+AggressiveHeap -Xms2000M -Xmx2000M -Doracle.j2ee.dont.use.memory.archive=true

On a 2 CPU dual core server (ie. 4 cores in total).

The mx and ms setting we set to the max allowed by the OS. We are running 32-bit Linux on Intel/AMD architectures so approximately 2GB is max. If you are running Solaris you should be able to extend to approx. 3.5G according to Sun.

These settings hold for both 10gR2 and 10gR3 Application Server (ie. HTB V5 and 6).

The rule of thumb we are using is that for each database CPU core you will need two application server CPU cores ie. if your database server is a 4 CPU dual core (8 cores) you should have four 2-way dual core boxes for the application server (16 cores in total). These figures are highly dependant on the nature of you application and does not include web-gui tier application load (eg. JSF / JSP load).

Another rule of thumb is that there needs to be approx. 500MB per core available for the JVM (or too much time will be spend garbage collecting). On Linux this means that if your application server hardware has more than 4 cores you should start more than one instance on the system eg. two instances on a 8 core box each with 2G memory allocated.

Last it is a good idea to limit the number of working threads to max 5 per core (thread pool) ie. 20 threads for a 2CPU dual core server. This will increase the total throughput because thread context changes are minimized under heavy load. I seem to remember that OC4J default to 80 threads.