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Comparison of Garbage Collection in Java 8 vs Java 17

Comparison of Garbage Collection in Java 8 vs Java 17

  • Default GC: Java 8 uses Parallel GC; Java 17 uses G1 GC.
  • Latency Options: Java 8 offers CMS; Java 17 includes ZGC and Shenandoah.
  • Heap Scalability: Java 8 supports medium heaps; Java 17 supports terabyte-scale heaps.
  • Concurrent Compaction: Available in Java 17 (ZGC, Shenandoah), not in Java 8.
  • Pause Times: Java 17 offers lower and more predictable pauses.

Comparison of Garbage Collection in Java 8 vs Java 17

Comparison of Garbage Collection in Java 8 vs Java 17
FeatureJava 8Java 17
Default GCParallel GCG1 GC
Low-Latency OptionCMSZGC, Shenandoah, G1
Heap Fragmentation HandlingLimitedAdvanced with ZGC and Shenandoah
Concurrent CompactionNot AvailableSupported by ZGC and Shenandoah
Heap ScalabilityUp to Medium-Sized HeapsSupports Terabyte-Scale Heaps
Pause Time PredictabilityModerate (CMS)High (G1, ZGC, Shenandoah)
Configuration ComplexityRequires Extensive TuningMinimal Tuning with Modern Collectors

Practical Benefits of Java 17’s Garbage Collection

1. Enhanced Performance for Modern Applications

Java 17’s collectors—G1, ZGC, and Shenandoah—are designed to handle modern workloads like real-time analytics, cloud-native applications, and large-scale data processing with minimal overhead and maximum efficiency.

2. Simplified Configuration

With advanced collectors like ZGC and Shenandoah, developers no longer need to spend excessive time fine-tuning GC settings. These collectors adapt intelligently to application needs.

3. Better Support for Large-Scale Applications

The ability of ZGC to handle terabyte-scale heaps ensures seamless scalability for enterprise applications, a critical feature for businesses managing vast datasets.

4. Reduced Latency in Real-Time Systems

Applications requiring consistent, low-latency performance benefit significantly from ZGC’s sub-millisecond pauses and Shenandoah’s concurrent heap compaction.


Migration Considerations: Java 8 to Java 17

Migration Considerations Java 8 to Java 17

Why Upgrade?

  • Advanced GC Options: Modern collectors in Java 17 provide better performance, scalability, and predictability.
  • Long-Term Support: As an LTS release, Java 17 ensures extended updates and stability.
  • Developer Productivity: New JVM features and enhanced performance reduce development and operational overhead.

Key Points to Assess Before Migration:

  1. Application Profile: Evaluate your application’s memory usage patterns to identify the most suitable GC.
  2. Testing and Benchmarking: Conduct performance tests with various collectors in Java 17 to determine the best fit.
  3. Configuration Updates: Adjust GC-related configurations to reflect default changes and tuning parameters.
  4. Dependency Compatibility: Ensure that all libraries and dependencies used by your application are compatible with Java 17.

Conclusion

The transition from Java 8 to Java 17 represents a substantial leap forward in garbage collection technology. Modern collectors like G1, ZGC, and Shenandoah offer enhanced performance, scalability, and predictability, addressing many of Java 8’s limitations.

With these advancements, Java 17 empowers developers to build and maintain highly responsive, scalable, and efficient applications. Upgrading to Java 17 is not just a step forward—it’s an essential move for leveraging the state-of-the-art memory management capabilities of the JVM.

Read our comparison of Java 8 vs 17 in performance.

FAQ: Comparison of Garbage Collection in Java 8 vs Java 17

What is the default garbage collector in Java 8 and Java 17?
Java 8 uses Parallel GC as the default, while Java 17 defaults to G1 GC.

Does Java 8 support low-latency garbage collection?
Yes, Java 8 supports CMS for low-latency applications but has limitations like heap fragmentation.

What low-latency options does Java 17 provide?
Java 17 offers ZGC and Shenandoah, which provide ultra-low pause times and advanced features.

Is concurrent heap compaction available in Java 8?
No, Java 8 does not support concurrent heap compaction. This feature is introduced in Java 17 with ZGC and Shenandoah.

Which version handles larger heaps better?
Java 17 supports terabyte-scale heaps, making it superior to Java 8, limited to medium-sized heaps.

What improvements does G1 GC in Java 17 have over Java 8?
Java 17’s G1 GC offers better throughput, lower latency, and improved pause time predictability compared to Java 8.

How does ZGC in Java 17 differ from garbage collectors in Java 8?
ZGC provides sub-millisecond pause times and scales to terabyte-sized heaps, features absent in Java 8.

Is Shenandoah available in Java 8?
No, Shenandoah is introduced in later Java versions and is part of Java 17.

Does Java 8 require more tuning than Java 17?
Yes, Java 8 collectors like CMS require extensive tuning, while Java 17’s modern collectors are more adaptive and require minimal configuration.

What are the pause time differences between Java 8 and Java 17?
Java 17 offers significantly lower and more predictable pause times than Java 8.

Can Java 17 collectors handle real-time applications better than Java 8?
ZGC and Shenandoah in Java 17 are specifically designed for real-time and low-latency applications.

Is CMS in Java 8 better than ZGC or Shenandoah in Java 17?
CMS was groundbreaking for its time but has been surpassed by ZGC and Shenandoah in terms of scalability, latency, and compaction.

Which version is more suitable for microservices?
Java 17 is better for microservices due to its low-latency collectors and better scalability.

How do garbage collectors in Java 17 handle heap fragmentation?
Collectors like ZGC and Shenandoah compact the heap concurrently, avoiding fragmentation issues seen in CMS.

Should I upgrade from Java 8 to Java 17 for better garbage collection?
Java 17 offers advanced garbage collectors, better performance, and long-term support, making it a valuable upgrade for most applications.

Author
  • Fredrik Filipsson has 20 years of experience in Oracle license management, including nine years working at Oracle and 11 years as a consultant, assisting major global clients with complex Oracle licensing issues. Before his work in Oracle licensing, he gained valuable expertise in IBM, SAP, and Salesforce licensing through his time at IBM. In addition, Fredrik has played a leading role in AI initiatives and is a successful entrepreneur, co-founding Redress Compliance and several other companies.

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