Concurrent Garbage Collectors: ZGC & Shenandoah
summary
Overview of two new Java concurrent compacting garbage collectors: ZGC (Linux x64 only) which uses colored pointer bits and a load barrier, and Shenandoah (multi‑architecture, included in OpenJDK 12) which uses Brooks-style forwarding pointers with read/write barriers. Both perform concurrent mark, relocate and remap to minimize stop‑the‑world pauses; on a 48 GB heap with ~3 GB/s allocation ZGC showed max pauses around 2.0 ms and Shenandoah around 4.0 ms, compared with G1 pauses of ~33–35 seconds on the same workload.
AI-written summary · about
chapters (8)
- 0:00Garbage collector intro
- 5:37Traditional GC problems
- 10:12ZGC features
- 23:29ZGC phases
- 29:54Shenandoah origins
- 36:21Shenandoah phases
- 43:50Shenandoah modes
- 47:32Benchmark results
related talks
47mConcurrent Garbage Collectors: ZGC & Shenandoah
01h 01mOpenJDK: In the new age of Concurrent Garbage Collectors
19mZ Garbage Collector: The Next Generation
46mZGC: A Scalable Low-Latency Garbage Collector
39mZGC: The Next Generation Low-Latency Garbage Collector
56mShenandoah: The Garbage Collector That Could
45mNew GC Algorithms in Java
52mGarbage collection for the humans