Hello All,

Could somebody please clarify on below questions about 'PermGen' space in JVM?

- Is it part of JVM heap or is it considered separate area? If it is separate, where does the PermGen memory get collected?
- Does it store the classes and class objects used by the JVM in runtime?

Thank you in advance.

Looks this is Solaris

- Is it part of JVM heap or is it considered separate area? If it is separate, where does the PermGen memory get collected?
>>> it comes from outside of the java heap
>>> it gets collected as part of full gc cycles

- Does it store the classes and class objects used by the JVM in runtime?
Yes it does store them in permgen 

Hi Archie882,


Thank you for clarifying. Just one another question.

Memory is decided by the address space, which depends on hardware architecture of the machine. If it is 32 bit hardware, it can give only upto 4 GB. Out of 4 GB, OS takes away some memory (for storing OS libraries). Rest available memory is split into JVM heap (for allocating objects created in runtime)and native memory (for storing non-java classes, JIT needed for the JVM). So, taking a deep dive, where does 'PermGen' get allocated/stored?

Permanent Generation Contains objects that may survive the entire life of the JVM
Actual classes and methods, classloaders, class variables
Physically, an independent and separately allocated region of storage from Main Heap.
so it is a region that is an independent area in the 4G region but managed by java.


www-01.ibm.com/support/docview.wss?uid=s...

Hi Archie882,

Thanks for the information and the link. It makes sense now :)