java heap space for a concurrent program - r12.2

[satish]

Dear Erman,

we are increasing the heap space for java spread sheet concurrent program using below steps.

To set the heap size for the porgram:
1. System Administrator -> Concurrent program -> Define -> Query for short name "EGOIJAVA"
2. If the Options field under executable region is blank, add "-Xmx2048m -Xms256m"
3. Save.


We need your support in understanding, if this memory what we have allocated will be taken from OS?

[oraprod@prod ~]$ free -g
              total        used        free      shared  buff/cache   available
Mem:            251          18          35          27         197         200
Swap:           255           0         255
[oraprod@erpproddb1 ~]$


Thank you

[ErmanArslansOracleBlog]

The memory that you are allocated is taken from your physical memory.
It is allocated by OS from your physical memory.

So, it is correct to check the memory using free command.
however, please read java documentation about Xmx and Xms parameters.
Xmx is the max value.
Xms it the initial allocation value.

Still, you may not see the memory allocation of the jvm memory until it is really allocated.
The space reserved for Java Heap is not immediately allocated in RAM.
So when the Java Heap is not used, it wont consume memory.