Book Image

Java Memory Management

By : Maaike van Putten, Dr. Seán Kennedy
Book Image

Java Memory Management

By: Maaike van Putten, Dr. Seán Kennedy

Overview of this book

Understanding how Java organizes memory is important for every Java professional, but this particular topic is a common knowledge gap for many software professionals. Having in-depth knowledge of memory functioning and management is incredibly useful in writing and analyzing code, as well as debugging memory problems. In fact, it can be just the knowledge you need to level up your skills and career. In this book, you’ll start by working through the basics of Java memory. After that, you’ll dive into the different segments individually. You’ll explore the stack, the heap, and the Metaspace. Next, you’ll be ready to delve into JVM standard garbage collectors. The book will also show you how to tune, monitor and profile JVM memory management. Later chapters will guide you on how to avoid and spot memory leaks. By the end of this book, you’ll have understood how Java manages memory and how to customize it for the benefit of your applications.
Table of Contents (10 chapters)


In this chapter, we have gone through an overview of Java memory. We started with computer memory and learned that the computer has main memory and secondary storage. The main memory is most important for us since this is what is used to run programs, including Java programs.

The main memory consists of RAM and ROM. Java applications use RAM to run. Java applications are executed by the JVM. This JVM executes Java applications and in order to do so, it has three components: a class loader, runtime data areas, and an execution engine.

We focused on the different components of the runtime data area: the heap, stack, method area, PC register, and native method stack.

The stack is the memory area that is used to store variables and values of methods in frames. The heap is used for storing objects. The stack holds references to objects on the heap. The heap is accessible from everywhere within the application and whoever has an object’s address on the heap can access...