Garbage Collection in Java: A Complete 4 Step Guide

Introduction

Whether you’re a coding enthusiast or someone who is considering making a career as a Coder, you must have come across the term ‘Garbage Collection in Java’ at some point while learning Java programming language. Let’s understand its meaning and application.

Definition

Garbage collection in Java or Java GC, in layman’s terms, refers to the technique used by the Java garbage collector to reclaim the unused runtime memory automatically. Whether they are using C, C++, or Java, programmers need to create and destroy objects to run a program successfully. However, programmers usually neglect object destruction. This can lead to OutOfMemoryErrors, which can cause a program to stop abruptly while running as there will be no sufficient memory available to create new objects. Thus, the need for garbage collection in Java, or in any programming language becomes pertinent.

Luckily, in Java, programmers don’t have to worry about unwanted objects. Here, the objects are created in the heap space when the programs run on Java Virtual Machine or a JVM. Heap space is a small portion of the memory dedicated to running the Java program on the JVM. A garbage collector automatically carries out the process of collecting garbage, i.e, unwanted objects, and destroys them.

In this article, we’ll be answering the following questions related to Garbage Collection in Java –

1. How does Garbage Collection in Java Work?
2. What are the Different Types of Garbage Collectors in Java?
3. What are the Benefits of Using Garbage Collection in Java?
4. What are the Best Practices of Java Garbage Collection?

Let’s get started!

1. How does Garbage Collection in Java Work?

As mentioned, the GC method in Java is automatically carried out by a garbage collector. It performs the operation of destroying or cleaning unwanted objects by employing Java GC to work on mark-and-sweep algorithms. A mark-and-sweep garbage collection algorithm in Java has to carry out two operations. First, it has to mark or identify unwanted objects. Second, it has to reclaim the heap space used by unwanted objects by sweeping or destroying them. To be able to explain garbage collection in Java, you’ll need to learn the various types of garbage collectors in Java first.

2. What are the Different Types of Garbage Collectors in Java?

 There are four different types of garbage collection in Java.  They are:

• Serial garbage collector: Serial garbage collector uses a single thread to carry out garbage collection.
• Parallel garbage collector: Parallel garbage collector is the default garbage collector in Java. It uses multiple threads to carry out the garbage collection process.
• CMS Java garbage collector: The Concurrent Mark Sweep or CMS Java garbage collector uses the same algorithm as a parallel garbage collector. However, the CMS garbage collector requires more CPU power than parallel garbage collectors. 
• G1 garbage collector: The G1 garbage collector was introduced as a replacement for the CMS garbage collector in JDK 1.7. It is used for large heap memory areas.

You can choose any of the different types of garbage collectors in Java, depending on your need for garbage collection in Java.

3. What are the Benefits of Using Garbage Collection in Java?

• Automation: The most significant benefit of the GC method in Java is that it automatically carries out the process of deletion of unwanted objects. As a programmer, you won’t have to delete objects manually and can, thus, utilize your time elsewhere.
• Memory efficiency: As the Java GC removes objects from the heap automatically, it results in better memory management. Your Java programs perform better due to memory being efficiently utilized due to garbage collection.

4. What are the Best Practices of Java Garbage Collection?

As a programmer, it is important to understand the best practices for garbage collection, even though the process doesn’t require a programmer to execute commands. The best practice to adopt when it comes to the GC method in Java is to set flags on the JVM. Flags can be used to adjust the garbage collector (CMS, G1 garbage collector, etc.), the size of the heap space, and its initial and maximum value.

Summary

• Garbage collection in Java is an important feature that ensures that the Java program never faces memory errors.
• The process of garbage collection is autonomous and helps save manual work.
• There are four types of garbage collectors in Java and programmers can choose one depending on their needs.
• Programmers need to set flags on the JVM to ensure efficient garbage collection. 

We hope this blog helped you understand the concept of automatic garbage collection in Java. If you are interested in learning more about software development, you can check out our holistic Master Certificate Program in Full Stack Development.