Episode 54 “How JDK 26 Improves G1's Throughput” [AtA]

Posted on April 9, 2026



G1 is Java’s default garbage collector in most environments, and its throughput has been considerably improved in JDK 26 by streamlining its write barriers. This conversation explores the background of that change and dives deep into regions, write barriers, concurrent marking, card tables, and how all that impacts throughput before eventually getting to the improvements made in Java 26, which lay further groundwork to G1 becoming the one and only default collector across all environments.

In this “Ask the Architect” episode of the Inside Java Podcast, recorded during JavaOne 2026, Nicolai Parlog talks to Stefan Johansson, HotSpot Garbage Collection engineer at Oracle.

JEP 522: https://openjdk.org/jeps/522


Make sure to also check the Duke’s Corner podcast on dev.java.


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