Garbage Collectors

2026

• Episode 59 “Java *is* Memory Efficient” [AtA] by Nicolai Parlog on May 28, 2026
• JEP targeted to JDK 27: 523: Make G1 the Default Garbage Collector in All Environments by Thomas Schatzl on May 26, 2026
• Episode 54 “How JDK 26 Improves G1's Throughput” [AtA] by Nicolai Parlog on April 9, 2026
• JDK 26 G1/Parallel/Serial GC changes by Thomas Schatzl on February 28, 2026
• Dissecting the CPU-Memory Relationship in Garbage Collection by Jonas Norlinder on February 24, 2026

2025

• Garbage Collection in Java: Choosing the Correct Collector by Stefan Johansson on November 29, 2025
• JEP targeted to JDK 26: 516: Ahead-of-Time Object Caching with Any GC by Erik Österlund on November 13, 2025
• JEP targeted to JDK 26: 522: G1 GC: Improve Throughput by Reducing Synchronization by Ivan Walulya, Thomas Schatzl on November 5, 2025
• NUMA-Aware Relocation in ZGC by Joel Sikström on October 24, 2025
• Three Upcoming G1 Improvements - Inside Java Newscast #99 by Nicolai Parlog on October 23, 2025
• Evolving ZGC's Pointer Color Palette #JVMLS by Erik Österlund on October 6, 2025
• JDK 25 G1/Parallel/Serial GC changes by Thomas Schatzl on September 8, 2025
• GC-Agnostic Load Barriers for Ahead-of-Time Compilation by Paul Hübner on August 27, 2025
• ZGC - Paving the GC On-Ramp by Erik Österlund on July 10, 2025
• Quality Outreach Heads-up - Separate Metaspace and GC Printing by Billy Korando on June 9, 2025
• Java 24, Faster Than Ever by Per-Ake Minborg on May 17, 2025
• Mastering JVM Memory Troubleshooting - From OutOfMemoryErrors to Leaks by Poonam Parhar on May 15, 2025
• Garbage Collection in Java: The Performance Benefits of Upgrading by Stefan Johansson on May 14, 2025
• How ZGC Allocates Memory for the Java Heap by Joel Sikström on April 17, 2025
• JDK 24 G1/Parallel/Serial GC Changes by Thomas Schatzl on April 7, 2025
• New Write Barriers for G1 by Thomas Schatzl on April 2, 2025
• Java 24 Release Notes Overview for Operations by Billy Korando on March 29, 2025
• How Can Machine Learning Assist to Improve JVM Performance by Yagmur Eren on March 9, 2025
• Garbage Collection in Java - The progress since JDK 8 by Stefan Johansson on February 15, 2025
• Quality Outreach Heads-up - JDK 25: Proposal to Deprecate for Removal -UseCompressedClassPointers by Billy Korando on February 6, 2025
• JVM Tuning with Machine Learning on Garbage Collection Logs by Yagmur Eren on January 13, 2025
• Using Buddy Allocators to Reduce Inter-Page Fragmentation in ZGC by Casper Norrbin on January 8, 2025

2024

• Mark–Scavenge: Waiting for Trash to Take Itself Out by Jonas Norlinder, Erik Österlund, Tobias Wrigstad on November 22, 2024
• ZGC Automatic Heap Sizing #JVMLS by Erik Österlund on November 9, 2024
• JEP targeted to JDK 24: 490: ZGC: Remove the Non-Generational Mode by Axel Boldt-Christmas on November 1, 2024
• JEP targeted to JDK 24: 475: Late Barrier Expansion for G1 by Roberto Castañeda Lozano, Erik Österlund on October 18, 2024
• Java's Fraught Relationship with Cyclic Object Graphs by Stuart Marks on October 15, 2024
• Project Lilliput - Beyond Compact Headers #JVMLS by Roman Kennke (guest) on September 6, 2024
• JDK 23 G1/Parallel/Serial GC changes by Thomas Schatzl on July 24, 2024
• Addressing Fragmentation in ZGC through Custom Allocators by Joel Sikström (guest) on June 19, 2024
• JEP targeted to JDK 23: 474: ZGC: Generational Mode by Default by Axel Boldt-Christmas on May 7, 2024
• JDK 22 in Two Minutes! - Sip of Java by Billy Korando on March 21, 2024
• Netflix - Bending Pause Times to Your Will with Generational ZGC by Danny Thomas (guest) on March 6, 2024
• When Should a Compiler Expand Garbage Collection Barriers? by Roberto Castañeda Lozano on February 16, 2024
• JDK 22 G1/Parallel/Serial GC changes by Thomas Schatzl on February 9, 2024

2023

• JDK 21: The GCs keep getting better by Stefan Johansson on December 14, 2023
• Java 22 Unpacking - Inside Java Newscast #59 by Nicolai Parlog on December 7, 2023
• JEP targeted to JDK 22: 423: Region Pinning for G1 by Hamlin Li (guest) on December 1, 2023
• Introducing Generational ZGC by Billy Korando on November 28, 2023
• Hazelcast Jet on Generational ZGC by Stefan Johansson on November 7, 2023
• Reducing P99 Latencies with Generational ZGC by Stefan Johansson on October 21, 2023
• G1: Java's Default Garbage Collector - Stack Walker #4 by Billy Korando on October 15, 2023
• Generational ZGC - Sip of Java by Billy Korando on October 9, 2023
• What is… a Concurrent Undo Cycle by Thomas Schatzl on October 4, 2023
• Java 21 JVM and GC Improvements #RoadTo21 by Billy Korando on September 3, 2023
• JVMLS - Generational ZGC and Beyond by Erik Österlund on August 31, 2023
• G1/Parallel/Serial GC improvements in JDK 21 by Thomas Schatzl on August 10, 2023
• Optimizing Memory Utilization with Automated Heap Sizing in ZGC by Marina Shimchenko (guest) on June 20, 2023
• Preserving the Mental Map when Visualizing Dynamic Graphs by Emmy Yin (guest) on June 12, 2023
• All That is in Java 21?! - Inside Java Newscast #50 by Nicolai Parlog on June 8, 2023
• UseDynamicNumberOfCompilerThreads and Memory Footprint by Poonam Parhar on May 30, 2023
• Save 10-20% Memory With Compact Headers - Inside Java Newscast #48 by Nicolai Parlog on May 11, 2023
• JEP proposed to target JDK 21: 439: Generational ZGC by Stefan Karlsson on May 4, 2023
• Z Garbage Collector: The Next Generation by Paul Su on April 23, 2023
• Throughput Analysis of Safepoint-attached Barriers in a Low-latency Garbage Collector by Filip Wilén (guest) on April 3, 2023
• G1/Parallel/Serial GC improvements in JDK 20 by Thomas Schatzl on March 17, 2023
• ZGC : Java’s Highly Scalable Low-Latency Garbage Collector - Stack Walker #1 by Billy Korando on March 5, 2023
• ZGC - The Future of Low-Latency Garbage Collection Is Here by Erik Österlund on January 25, 2023

2022

• Quality Outreach Heads-up - New Generational ZGC Early Access Builds by Stefan Karlsson on November 29, 2022
• Frequent Full GCs by Poonam Parhar on November 17, 2022
• Generational ZGC - Inside Java Newscast #37 by Billy Korando on November 17, 2022
• Generational ZGC Early-Access builds by Erik Österlund on October 18, 2022
• G1/Parallel/Serial GC improvements in JDK 19 by Thomas Schatzl on September 21, 2022
• G1 Pre-Barrier Implementation by Albert Yang on August 24, 2022
• Concurrent Marking in G1 by Thomas Schatzl on August 18, 2022
• The Serial Garbage Collector - Sip of Java by Billy Korando on August 8, 2022
• The Parallel Garbage Collector - Sip of Java by Billy Korando on August 1, 2022
• Mitigate the relocation degradations for cache locality improvement algorithm by Jinyu Yu (guest) on July 1, 2022
• Episode 24 “Towards Generational ZGC!” by Erik Österlund, David Delabassee on June 29, 2022
• The G1 Garbage Collector - Sip of Java by Billy Korando on June 20, 2022
• JDK GCs Comparison - Sip of Java by Billy Korando on June 6, 2022
• Concurrent Thread-stack Processing in the Z Garbage Collector by Erik Österlund on May 31, 2022
• ZGC, the JDK's Newest Garbage Collector - Sip of Java by Billy Korando on May 30, 2022
• JDK 8 to JDK 18 in Garbage Collection: 10 Releases, 2000+ Enhancements by Thomas Schatzl on May 2, 2022
• ZGC - What's new in JDK 18 by Per Liden on April 29, 2022
• ZGC - The Future of Low-Latency Garbage Collection Is Here by Per Liden on March 30, 2022
• G1/Parallel/Serial GC improvements in JDK 18 by Thomas Schatzl on March 16, 2022
• Card Table Card Size Shenanigans by Thomas Schatzl on February 16, 2022
• New candidate JEP: 423: Region Pinning for G1 by Mark Reinhold on February 2, 2022

2021

• Understanding Metaspace and Class Space GC Log Entries by Poonam Parhar on December 14, 2021
• GC progress from JDK 8 to JDK 17 by Stefan Johansson on November 24, 2021
• Heap Regions X-Large by Thomas Schatzl on November 15, 2021
• G1: To Infinity and Beyond by Stefan Johansson on October 11, 2021
• ZGC - What's new in JDK 17 by Per Liden on October 5, 2021
• G1 GC & Parallel GC Improvements in JDK 17 by Thomas Schatzl on September 17, 2021
• Large pages and Java by Stefan Johansson on May 19, 2021
• ZGC - What's new in JDK 16 by Per Liden on March 22, 2021
• G1 & Parallel GC Improvements in JDK 16 by Thomas Schatzl on March 15, 2021
• Welcome 20% less memory usage for G1 remembered sets - Prune collection set candidates early by Thomas Schatzl on February 26, 2021

2020

• NUMA-Aware Memory Allocation for G1 GC by Sangheon Kim on November 3, 2020
• Episode 5 “The Z Garbage Collector (ZGC)” with Per Liden by Per Liden, David Delabassee on October 14, 2020
• JEP proposed to target JDK 16: 376: ZGC: Concurrent Thread-Stack Processing by Mark Reinhold on September 24, 2020
• ZGC - What's new in JDK 15 by Per Liden on September 22, 2020
• ZGC: The Next Generation Low-Latency Garbage Collector by Per Liden on September 17, 2020
• JEP proposed to target JDK 16: 387: Elastic Metaspace by Mark Reinhold on September 10, 2020
• JDK 15 G1/Parallel GC changes by Thomas Schatzl on September 1, 2020
• Heap Snapshotting by Ludvig Janiuk (guest) on August 26, 2020
• New candidate JEP: 387: Elastic Metaspace by Mark Reinhold on July 7, 2020
• ZGC - Using -XX:SoftMaxHeapSize by Per Liden on July 2, 2020
• How do 'hot and cold' objects behave? by Hanna Nyblom (guest) on July 1, 2020
• Compact Forwarding Information by Jonas Norlinder (guest) on June 25, 2020
• Oracle, Uppsala University, and KTH in joint JVM research projects by Jesper Wilhelmsson on June 12, 2020
• Improving G1 out-of-the-box performance by Stefan Johansson on April 16, 2020
• ZGC - What's new in JDK 14 by Per Liden on March 23, 2020
• Making ZGC Production Ready by Per Liden on February 20, 2020
• HotSpot Handshaking by Robbin Ehn on February 10, 2020
• G1: To infinity and beyond by Stefan Johansson on February 1, 2020

2019

• A critical question, Zee GC or Zed GC? by Per Liden on October 4, 2019
• ZGC and tmpfs/hugeltbfs by Per Liden on June 28, 2019
• ZGC Concurrent Class Unloading by Erik Österlund on February 4, 2019

2018

• The Z Garbage Collector by Erik Österlund on November 17, 2018
• ZGC : A Scalable Low-Latency Garbage Collector by Per Liden on October 25, 2018

2017

• Can young generation size impact response times? by Poonam Parhar on December 11, 2017