In this post, we will explore two important features of the Shenandoah Garbage Collector (GC) - Concurrent Weak Root Processing and Concurrent Weak Processing. These features greatly contribute to the efficiency and performance of the GC in handling weak references.
Table of Contents
Introduction to Shenandoah GC
Shenandoah GC is a low-pause time garbage collector developed by the OpenJDK community. It is designed to minimize the GC pauses, allowing applications to handle large heaps with minimal impact on responsiveness. One of the key features of Shenandoah GC is its concurrent nature, which enables it to run concurrently with application threads, keeping pause times short and predictable.
Concurrent Weak Root Processing
Weak references are a type of reference in Java that allows objects to be garbage collected even if they are only weakly reachable. Weak root references are weak references that are stored in the root set of the garbage collector. During garbage collection, the GC needs to process these weak roots to determine if the referenced objects are still reachable or can be collected.
In Shenandoah GC, the Concurrent Weak Root Processing feature allows the GC to process weak root references concurrently with the running application threads. This means that the GC can perform the necessary checks and adjustments without causing any stop-the-world pauses. This concurrent processing of weak root references helps in reducing the overall pause time of the GC.
Concurrent Weak Processing
In addition to weak root processing, the Shenandoah GC also provides Concurrent Weak Processing. Weak processing involves scanning weak reference objects and determining if the referenced objects are still reachable. Concurrent Weak Processing allows the GC to perform these scans concurrently with the running application threads.
By leveraging multi-threaded processing, the Shenandoah GC can parallelize the scanning of weak references, resulting in faster and more efficient scanning. This concurrent processing reduces the overall pause time of the GC and improves the application’s responsiveness.
Conclusion
Concurrent Weak Root Processing and Concurrent Weak Processing are two key features of the Shenandoah GC that contribute to its low-pause time and efficient garbage collection. These features allow the GC to process weak references concurrently, minimizing pause times and improving overall application performance.
Shenandoah GC is gaining popularity in the Java community due to its ability to provide predictable and low-latency garbage collection. By leveraging concurrent processing of weak references, Shenandoah GC enhances the performance of applications running with large heaps and weak references.
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