JDK 27 New Features: Vector API, G1GC Default

JDK 27 New Features: Vector API, G1GC Default

The OpenJDK ecosystem is moving fast. During the week of May 18th, 2026, six Java Enhancement Proposals (JEPs) advanced in the pipeline for JDK 27, one of the most active weekly periods this cycle. Three JEPs moved from Proposed to Target to Targeted, while three others stepped up from Candidate to Proposed to Target. Together, they form the core of JDK 27 new features taking shape ahead of the freeze date.

First, JEP 537, Vector API (Twelfth Incubator), is now targeted for JDK 27. This marks its twelfth incubation round, continuing a journey that began with JDK 16. It introduces an API that expresses vector computations compiling at runtime to optimal CPU instructions, outperforming equivalent scalar code. Notably, the Vector API will stay in incubation until Project Valhalla delivers its preview features. Only then will the team promote it to Preview status.

Next, JEP 534, Compact Object Headers by Default, moves to make the compact header layout introduced in JDK 25 the standard in the HotSpot JVM. This is a memory efficiency win for Java applications running at scale.

Then there is JEP 523, which proposes making the Garbage-First Garbage Collector (G1 GC) the default in all environments, not just server ones. Currently, if no garbage collector is specified on the command line, the HotSpot JVM picks G1 GC only in server environments. This JEP extends that behavior universally, which is one of the more impactful JDK 27 new features for application developers.

On the Proposed to Target side, JEP 538, PEM Encodings of Cryptographic Objects, finalizes an API for encoding and decoding cryptographic keys, certificates, and certificate revocation lists using the widely-used PEM transport format. After two preview rounds in JDK 25 and JDK 26, changes include reclassifying the PEM record class and renaming the DEREncodable interface to BinaryEncodable. The review closes May 27th, 2026.

Also proposed, JEP 536, JFR In-Process Data Redaction, enhances the JDK Flight Recorder to automatically redact sensitive data, such as command-line arguments and environment variable values, before recording completes. This directly addresses compliance and data privacy concerns in production environments. Review closes May 26th.

Finally, JEP 528, Post-Mortem Crash Analysis with jcmd, extends the jcmd tool to diagnose JVM crashes, reducing dependence on the jhsdb utility and the Serviceability Agent. However, its status may have reverted to Candidate with JDK 28 as the target; the JEP document updated on May 21st, the day after it was declared Proposed to Target. The situation remains fluid.

The JDK 27 release schedule, approved by Mark Reinhold, Chief Architect of Oracle’s Java Platform Group, sets Rampdown Phase One for June 4, 2026, with General Availability on September 14, 2026. With fewer than two weeks to the feature freeze, 10 JEPs now form the current JDK 27 new features set, including Post-Quantum Hybrid Key Exchange for TLS 1.3, Structured Concurrency (Seventh Preview), and Lazy Constants (Third Preview). JDK 27 will be the second non-LTS release since JDK 25.