java - Perm space vs Heap space

Question

First, What is the difference between Perm space and Heap space (What and how does the JVM choose to use each memory space)?

Second, but most importantly, what sort of ratio would be recommended for a standard MVC type java application?

Answer 1

The heap stores all of the objects created by your Java program. The heap's contents is monitored by the garbage collector, which frees memory from the heap when you stop using an object (i.e. when there are no more references to the object.

This is in contrast with the stack, which stores primitive types like ints and chars, and are typically local variables and function return values. These are not garbage collected.

The perm space refers to a special part of the heap. See this SO answer for an explanation: What is perm space?