I’m currently monitoring a Java application with jconsole. The memory tab lets you choose between:
Heap Memory Usage
Non-Heap Memory Usage
Memory Pool “Eden Space”
Memory Pool “Survivor Space”
Memory Pool “Tenured Gen”
Memory Pool “Code Cache”
Memory Pool “Perm Gen”
What is the difference between them ?
5 Answers
Heap memory
The heap memory is the runtime data area from which the Java VM allocates memory for all class instances and arrays. The heap may be of a fixed or variable size. The garbage collector is an automatic memory management system that reclaims heap memory for objects.
Eden Space: The pool from which memory is initially allocated for most objects.
Survivor Space: The pool containing objects that have survived the garbage collection of the Eden space.
Tenured Generation or Old Gen: The pool containing objects that have existed for some time in the survivor space.
