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Garbage collector improvements in Java 14

Java 14 introduced several enhancements and optimizations to the garbage collector, providing better performance and reducing memory overhead. In this blog post, we will explore the improvements made in Java 14’s garbage collection system.

ZGC Improvements

The ZGC (Z Garbage Collector) in Java 14 received some notable improvements. ZGC is a scalable garbage collector designed to handle large heaps and minimize pause times. Here are the enhancements in Java 14:

  1. Reduced Root Scanning Pause - The time taken to scan application roots during the garbage collection cycle has been significantly reduced. This means that the application can resume execution faster after a garbage collection pause.

  2. Concurrent Thread-Local Handshakes - ZGC now supports Thread-Local Handshakes, which allows application threads to cooperate with garbage collection. This enables finer-grained control over concurrent operations and can lead to shorter pause times.

Shenandoah GC Improvements

Shenandoah GC is another garbage collector introduced in Java 12, optimized for low-pause time requirements. Java 14 brings the following improvements to Shenandoah GC:

  1. Elastic Heap - Shenandoah GC in Java 14 introduces an elastic heap, which enables dynamic resizing of the heap during concurrent evacuation. This results in better memory utilization, as the heap can grow or shrink as needed to accommodate the application’s workload.

  2. Uncommit Unused Memory - In previous versions of Java, Shenandoah GC would not uncommit unused memory after a garbage collection cycle. Starting from Java 14, Shenandoah GC can uncommit unused memory, reducing the overall memory footprint of the application.

G1GC Improvements

Java 14 also brings some enhancements to the G1GC (Garbage First Garbage Collector). G1GC is a garbage collector aimed at providing good overall performance while keeping pause times low. Here are the improvements in Java 14:

  1. Parallel Full GC - G1GC now allows full garbage collections to be executed in parallel. This enhancement can greatly improve the throughput of the garbage collection process.

  2. Improved Allocation Efficiency - The allocation efficiency of G1GC has been improved in Java 14. This means that objects are allocated more efficiently, reducing memory fragmentation and improving overall performance.

Conclusion

Java 14 introduces significant improvements to the garbage collector, specifically in ZGC, Shenandoah GC, and G1GC. These enhancements aim to reduce pause times, improve memory utilization, and provide better overall garbage collection performance. If you are using Java 14 or planning to upgrade, these improvements can greatly benefit your application’s memory management.

References

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