Method Area and PermGen

java memory-management jvm jvm-hotspot permgen
Ratheesh P Kumar picture Ratheesh P Kumar · Feb 1, 2012 · Viewed 18.1k times · Source

I was trying to understand the memory structure of HotSpot JVM and got confused with the two terms "Method Area" and "PermGen" space. The docs I referred to say that Method Area contains the definition of classes and methods including the byte code. Some other docs say that they are stored in the PermGen space.

So can I conclude that these two memory areas are same?

Answer

xea picture xea · Feb 1, 2012

You should take a look at Java Memory Types and optionally at this doc about the Garbage Collection in Java. The latter is very verbose and both are useful.

Actually the Method area is a part of the Permanent Generation:

A third generation closely related to the tenured generation is the permanent generation. The permanent generation is special because it holds data needed by the virtual machine to describe objects that do not have an equivalence at the Java language level. For example objects describing classes and methods are stored in the permanent generation.

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