ZGC (Z Garbage Collector) is a scalable, low-latency garbage collector introduced in Java 11 and fully production-ready in later versions. It is designed to handle large heap sizes—ranging from a few hundred megabytes to multiple terabytes—while maintaining low pause times, typically under 10 milliseconds. This makes ZGC particularly suitable for latency-sensitive applications where predictable performance is critical.
ZGC operates concurrently with the application threads, minimizing the impact on application throughput. It achieves this by using colored pointers and load barriers to manage object references during garbage collection cycles. Unlike older garbage collectors such as G1 or CMS, ZGC does not require full heap scans during stop-the-world phases, allowing it to scale efficiently with large heaps.
- Enables sub-10ms pause times even with multi-terabyte heaps
- Runs most collection work concurrently with application threads
- Uses colored pointers and load barriers for efficient memory management
- Available in OpenJDK and supported in major JVM distributions
- Optimized for applications requiring high throughput and low latency
Professionals with expertise in ZGC are typically Java developers, performance engineers, or JVM specialists working on high-throughput systems such as financial trading platforms, real-time data processing pipelines, or large-scale microservices. They are expected to configure and tune ZGC settings, monitor garbage collection logs, and diagnose memory-related performance issues. Knowledge of JVM memory management, garbage collection algorithms, and tools like jstat, JFR (Java Flight Recorder), and GC log analyzers is essential for effective use of ZGC.
Industries that commonly use ZGC include fintech, telecommunications, cloud services, and e-commerce—sectors where application responsiveness and scalability are critical. As Java continues to evolve, ZGC is increasingly adopted in modern JVM-based applications aiming to balance memory efficiency with low-latency requirements.