JVM Paratmeters for Webcenter

Option	Detailed Description
-Xns (setting the Nursery)	We should try to make the nursery as large as possible while still keeping the garbage collection pause times acceptably low. This is particularly important for our application is creating a lot of temporary objects. The maximum size of a nursery cannot exceed 95% of the maximum heap size.
-Xms (Setting initial and minimum heap size)	Oracle recommends setting the minimum heap size (-Xms) equal to the maximum heap size (-Xmx) to minimize garbage collections.
-Xms (Setting maximum heap size)	Setting a low maximum heap value compared to the amount of live data decrease performance by forcing frequent garbage collections.
SoftRefLRUPolicyMSPerMB	Softly reachable objects will remain alive for some amount of time after the last time they were referenced. The default value is one second of lifetime per free megabyte in the heap. This value can be adjusted using the -XX:SoftRefLRUPolicyMSPerMB flag, which accepts integer values representing milliseconds. For example, to change the value from one second to 2.5 seconds, use this flag: -XX:SoftRefLRUPolicyMSPerMB=2500
Dweblogic.threadpool.MaxPoolSize	There are different ways of changing the size of thread pool.  One way of doing it is by setting them from the command line:     -Dweblogic.threadpool.MinPoolSize=5 -Dweblogic.threadpool.MaxPoolSize=5 By setting both MinPoolSize and MaxPoolSize to be the same value, we have forced WLS to use exactly five worker threads.

Note that the values of -Xmn and SoftRefLRUPolicyMSPerMB(0-1000) can aslo be adjusted in accordance with the respective application memory settings and requirements.

For example, If we start the WebLogic Server instance from a java command line, we can specify the heap size values as follows:

$ java -Xns10m -Xms512m -Xmx512m

The default size for these values is measured in bytes. Append the letter 'k' or 'K' to the value to indicate kilobytes, 'm' or 'M' to indicate megabytes, and 'g' or 'G' to indicate gigabytes.

The example above allocates 10 megabytes of memory to the Nursery heap sizes and 512 megabytes of memory to the minimum and maximum heap sizes for the WebLogic Server instance running in the JVM.