"Working with Java Virtual Machine" 读书笔记（一）

   在books24x7.com上在线看的这本书（不过不是免费的，IBM为员工买了这个网站的阅读权利），觉得有些东西有必要记下来。不知道有“一”还会不会有“二”，呵呵。
Chapter 2 Overview of JVM architecture, Section 2 Runtime Data Areas in JVM

JVM data area:
1. Method area
2. Heap
3. PC Register
4. Java Stack
5. Native Method Stack

Method area: Shared among all JVM thread
1. name
2. super class
3. class/interface
4. modifier
5. list of super interfaces
6. Other:
                a. Constant pool
                b. field info
                c. method info
                d. class var
                e. ref to Classloader
                f. ref to Class

Heap:
1. Handle pool: pointer to object(in object pool) & class(in method area)
2. Object pool (instances)
Such design is for the avoiding fragmentation

Stach: 2 types
1. Frame for func activation
2. Operand for instructions, arg & ret of JVM instruction

Java Stack Component
1. local var
2. execution env
3. operand stack

JDK -- JRE -- JVM -- bytecode Interpreter, GC, Class manager, ...
         /            /         
                         classlib -- byte code
                                         /
                                           native