The Z Garbage Collector - In JDK 25

This book explains how the Z Garbage Collector was designed, why it was designed this way, the common pitfalls to avoid when using ZGC in JDK 25 and how to get useful information from the garbage collector.
Java is one of the most widely used programming languages in the world. It is a memory safe language that completely relies on a good garbage collection (GC) algorithm to work well. The Z Garbage Collector of OpenJDK is arguably the most sophisticated production GC algorithm for any managed language runtime. The book goes into detail and covers core algorithm concepts of ZGC: coloured pointers, GC barriers, concurrent marking, concurrent relocation, concurrent stack scanning, concurrent root scanning, concurrent class unloading, concurrent generational collection, as well as showing how all of this works. It explains how the JVM evolved certain features to be able to accommodate ZGC, and covers the importance of each of the various GC heuristics and how they function.
With a unique angle right between academia and industry, this book is useful for computer science students and Java developers alike.

List of contents

1. Introduction 2. ZGC Design Overview 3. ZGC Memory Layout 4. ZGC Generations 5. ZGC Barriers 6. ZGC Collection Phases 7. ZGC Root Scanning 8. ZGC Class Unloading 9. ZGC Collection Triggers 10. ZGC Thread Sizing Heuristics 11. ZGC Heap Sizing Policies 12. Safepoint Polls 13. Thread-Local Handshakes 14. Compiled Method Entry Barriers 15. Compiled Barriers 16. Virtual Threads 17. Deploying ZGC 18. Measuring Latency 19. Measuring Throughput 20. Measuring Memory Footprint 21. Observability 22. ZGC Heap Sizing

About the author

Erik Österlund is a Consulting Member of Technical Staff, Oracle.

Product details

• Authors: Erik Österlund
• Publisher: Taylor and Francis
• Languages: English
• Product format: Paperback / Softback
• Release: 22.05.2026
• EAN: 9781032976921
• ISBN: 978-1-032-97692-1
• No. of pages: 384
• Illustrations: schwarz-weiss Illustrationen, Zeichnungen, schwarz-weiss, Tabellen, schwarz-weiss
• Subjects: Natural sciences, medicine, IT, technology > IT, data processing > Programming languages; Software Engineering, COMPUTERS / Computer Science, COMPUTERS / Software Development & Engineering / General, COMPUTERS / Programming / Algorithms, computer science, COMPUTERS / Software Development & Engineering / Tools, algorithms and data structures, Algorithms & data structures, Information technology: general issues, Programming & scripting languages: general, Programming and scripting languages: general, COMPUTERS / Languages / Java, Digital and Information technology: general topics