?️ Garbage Collection Algorithms

? Quick Overview

Garbage Collection (GC) in Java is an automatic memory management process. The JVM uses different GC algorithms to reclaim unused objects, optimize memory usage, and minimize application pause times.

? Key Concepts

• Heap is divided into Young Generation and Old Generation
• Minor GC works on Young Generation
• Major / Full GC works on Old Generation
• Different algorithms focus on throughput, latency, or footprint

? Syntax / Theory

GC algorithms are selected using JVM flags. Each algorithm has different behavior in terms of pause time, memory usage, and CPU overhead.

Common GC Algorithms

• Serial GC – Single-threaded, simple
• Parallel GC – High throughput
• CMS – Low pause (deprecated)
• G1 GC – Balanced, region-based
• ZGC – Ultra-low latency

? Code Example(s)

// Example JVM options to enable G1 Garbage Collector
java -XX:+UseG1GC -Xms512m -Xmx1024m -jar app.jar

// Simple Java program to create objects and trigger GC
public class GCExample {
public static void main(String[] args) {
for (int i = 0; i < 100000; i++) {
byte[] data = new byte[1024 * 1024];
}
System.out.println("Objects created");
}
}

? Live Output / Explanation