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Sharath Kumar
Sharath Kumar

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What Are Different Garbage Collectors in JVM

1. Introduction

Garbage Collection in Java is an automatic memory management process that removes unused objects from memory. The JVM provides different types of Garbage Collectors, each designed for specific use cases and performance requirements.

2. What is Garbage Collection in JVM

Garbage Collection is the process of identifying and removing objects that are no longer in use, freeing up memory and improving application efficiency.

Summary

Automatically manages memory.
Removes unused objects.
Prevents memory leaks.


3. Types of Garbage Collectors in JVM

3.1 Serial Garbage Collector

The Serial GC uses a single thread to perform all garbage collection tasks. It is suitable for small applications with low memory requirements.

Summary

Single threaded.
Simple and low overhead.
Best for small applications.


3.2 Parallel Garbage Collector Throughput Collector

The Parallel GC uses multiple threads to perform garbage collection, improving throughput and performance.

Summary

Multi threaded.
High throughput.
Used in applications where performance is important.


3.3 CMS Garbage Collector Concurrent Mark Sweep

CMS GC performs most of its work concurrently with the application, reducing pause times.

Summary

Low pause time.
Runs alongside application.
May cause fragmentation.


3.4 G1 Garbage Collector Garbage First

G1 GC divides heap into regions and prioritizes garbage collection in areas with the most garbage. It is designed for large applications.

Summary

Region based.
Low pause times.
Best for large heaps.


3.5 Z Garbage Collector ZGC

ZGC is a modern low latency garbage collector designed for very large applications. It minimizes pause times to a few milliseconds.

Summary

Ultra low latency.
Handles large heaps.
Highly scalable.


3.6 Shenandoah Garbage Collector

Shenandoah GC focuses on reducing pause times by performing most of its work concurrently with the application.

Summary

Low pause time.
Concurrent processing.
Improves responsiveness.


4. Comparison of Garbage Collectors

Garbage Collector Best For Key Feature
Serial GC Small apps Single thread
Parallel GC High throughput apps Multi thread
CMS GC Low latency apps Concurrent execution
G1 GC Large applications Region based
ZGC Very large apps Ultra low pause
Shenandoah Responsive apps Concurrent GC

5. How to Choose the Right GC

Use Serial GC for small applications.
Use Parallel GC for high throughput.
Use G1 GC for balanced performance.
Use ZGC or Shenandoah for low latency systems.


6. Common Mistakes to Avoid

Choosing wrong GC for application type.
Ignoring GC tuning.
Not monitoring memory usage.


7. Key Takeaways

JVM provides multiple Garbage Collectors.
Each GC has its own use case.
Choosing the right GC improves performance.
Modern GCs focus on low latency.


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9. FAQ Section

9.1 What is Garbage Collection in Java

Garbage Collection is the process of automatically removing unused objects from memory to free up space.

9.2 Which Garbage Collector is best in Java

G1 GC is commonly used as a default because it provides a good balance between performance and latency.

9.3 What is the difference between Serial and Parallel GC

Serial GC uses a single thread, while Parallel GC uses multiple threads for better performance.

9.4 What is low latency Garbage Collector

Low latency collectors like ZGC and Shenandoah minimize pause times to improve application responsiveness.

9.5 Can we change Garbage Collector in Java

Yes, you can choose different Garbage Collectors using JVM options based on application needs.


10. Conclusion

Understanding different Garbage Collectors in JVM helps you optimize memory management and application performance. By selecting the right GC, you can achieve better throughput and lower latency.

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