JDK 27 Released: G1 GC Is Now the Default, Compact Object Headers & Post-Quantum TLS — Should You Upgrade?
On September 15, 2026 , JDK 27 reached general availability — the 18th feature release in a row to ship on Java's six-month cadence. It carries nine JEPs, but the headline is not the count. It is this: JDK 27 is the release where Java stops asking you to opt in to good defaults and turns them on. Two of the four finalized JEPs quietly change how your running services behave without you touching a line of code — and a third hardens every TLS connection your apps make against quantum computers. If your services run in small containers and you never set a GC flag, this release changes your garbage collector. Read on before you bump the base image. The release at a glance Four JEPs are final and active with no special flags; the rest stay in preview or incubator, meaning their APIs can still change: JEP Feature Status 523 Make G1 the default garbage collector in all environments Final 527 Post-quantum hybrid key exchange for TLS 1.3 Final 534 Compact object headers by defa...