Java Memory Management: Understanding the JVM, Heap, Method Area, Stack

JVM heap memory structure(image source:javatpoint.com)

If you are new to Java, I would recommend you to go through the 5 min read Getting started with java first, that will give an idea of what is JDK, JRE and JVM.

If you are wondering when the JVM will come into picture, the JVM instance is generated when you run the class file using the java command after compiling the Java program to create the .class file using JDK.

JVM basically loads the code into memory, verifies code, executes code and provides runtime environment.

JVM contains the classloader, memory area, execution engine,etc as shown in below JVM architecture diagram.

JVM Architecture (image source:getsurejavaj2ee.blogspot.com)

As you see in the above diagram, the Runtime Data Access which is nothing but the Memory Area that has been divided into multiple parts called as Method Area, Heap , PCS (Program Counter Registers, and Native Method Stack to manage and optimize the allocation and use of memory.

Let us discuss each of the memory areas below.

Heap:

• The heap is the main area of memory used by the JVM to store objects and their associated data.