"Adaptive Heap Sizing + Numeric Conversion + Primitive Patterns" [IJN]

JDK 28's adaptive heap sizing for ZGC dynamically balances CPU use and memory consumption with close-to-zero configuration. Value classes introduce new challenges for conversions between custom numeric types, which type classes could eventually address, but unresolved questions about how these features should interact mean that primitive patterns won't return in JDK 28 and will instead be withdrawn. 😟 Other highlights are upcoming Java events and JDK 28's planned features.

Links:

Adaptive heap sizing for ZGC:

• JEP 546 - Adaptive Heap Sizing for ZGC: https://openjdk.org/jeps/546

Java events:

• FOSDEM: https://wiki.debian.org/Java/DevJam/2027/Fosdem
• JVMLS: https://openjdk.org/projects/mlvm/jvmlangsummit/
• JavaOne tickets: https://www.oracle.com/javaone/register/

Value classes, numeric conversions, primitive patterns:

• JLS on conversions: https://docs.oracle.com/en/java/javase/27/docs/specs/jls/jls-5.html
• Brian Goetz on type classes: https://www.youtube.com/watch?v=Gz7Or9C0TpM
• Amber mail on primitive patterns: https://mail.openjdk.org/archives/list/[email protected]/thread/UYEK3PGOHN6R56AHJTSLPGAY363K666S/
• Amber mail on constant patterns: https://mail.openjdk.org/pipermail/amber-spec-experts/2026-January/004306.html

JDK 28:

• early-access builds: https://jdk.java.net/28/
• feature list: http://openjdk.org/projects/jdk/28/