LuTiao Programming

Aug 25, 2026 · Fundamentals

Why Java 27’s Compact Object Headers Reduce Object Header Size from 12 B to 8 B

Java 27 enables Compact Object Headers, shrinking the default 64‑bit object header from 12 bytes to 8 bytes, which can noticeably lower heap usage for object‑heavy services; the article explains the layout change, demonstrates it with JOL, and offers practical testing guidance for real‑world applications.