JEP 474 proposes a significant enhancement to the Z Garbage Collector (ZGC) by making generational mode the default mode of operation. This change aims to improve the performance and efficiency of ZGC, especially for workloads that benefit from generational garbage collection strategies.
Here’s a breakdown of what this JEP entails:
- Z Garbage Collector (ZGC): ZGC is a low-latency garbage collector developed by Oracle for OpenJDK. It is designed to keep pause times consistently low even with very large heaps, making it suitable for applications requiring low latency and high scalability.
- Generational Garbage Collection: Generational garbage collection is a strategy that divides the heap into two or more generations (typically young and old generations). Objects are initially allocated in the young generation, and most objects die young, which allows for efficient collection of short-lived objects.
- Default Mode: Currently, ZGC operates in a single-generation mode, treating the entire heap as a single generation. This mode has benefits for certain workloads but may not be optimal for all scenarios.
- Advantages of Generational Mode:
- Compatibility and Migration: The JEP would ensure that applications currently using ZGC’s single-generation mode can seamlessly migrate to the new default generational mode without requiring significant changes.
- Configuration Options: While generational mode would become the default, users can still configure ZGC to operate in a single-generation mode if needed for specific use cases or compatibility reasons.
In summary, JEP 474 proposes a valuable enhancement to ZGC by switching its default mode of operation to generational garbage collection. This change is expected to benefit a wide range of applications, particularly those requiring low-latency and scalable garbage collection.