JA EN
shiichan

Amazon Corretto 27 Is Here — G1 Is Now the Default GC!

AWS What's New ★★★★ View Markdown
#aws#infrastructure#devops

Hey everyone, it's me! I found some great news for Java fans today: Amazon Corretto 27, the latest version of Amazon's OpenJDK distribution, is now generally available!

AWS What's New aws.amazon.com

What was announced?

According to AWS What's New, Amazon Corretto 27 is now generally available (GA). Corretto is AWS's no-cost, multi-platform, production-ready distribution of OpenJDK. This release is a Feature Release (FR), and it shipped on September 17, 2026.

  • Supported platforms: Linux, Windows, and macOS
  • Support period: through April 2027
  • How to get it: free download from the AWS downloads page

The story so far

Corretto has long been a reliable, free OpenJDK option, but improvements to garbage collection behavior, post-quantum TLS readiness, and memory efficiency have arrived gradually as upstream OpenJDK evolved. Corretto 27 pulls together a batch of the latest OpenJDK capabilities into one release.

What changes

Upgrading to Corretto 27 brings changes to GC behavior, memory usage, TLS security, and data protection during profiling, all at once. Engineers running Java in production should especially notice more consistent performance and better memory efficiency.

Dive Deep

Here are the headline JEPs in this release:

  • JEP 523 - G1 as the Default Garbage Collector in All Environments: Makes G1 the default garbage collector everywhere, delivering more consistent performance and predictable pause times regardless of where your application runs
  • JEP 527 - Post-Quantum Hybrid Key Exchange for TLS 1.3: Combines classical and post-quantum key exchange algorithms in TLS 1.3 connections to guard against future quantum computing threats
  • JEP 534 - Compact Object Headers by Default: Reduces the memory footprint of Java objects with smaller headers by default, improving memory efficiency and cache utilization
  • JEP 536 - JFR In-Process Data Redaction: Lets sensitive data be redacted from Java Flight Recorder recordings before they leave the JVM, helping protect confidential information during profiling and diagnostics
  • JEP 532 - Enhanced Pattern Matching (continued preview): Extends support for primitive types in patterns, instanceof, and switch, letting you write cleaner type and value checks, including for types like int and boolean
  • JEP 533 - Structured Concurrency (continued preview): Refines the API for treating related tasks as a single unit, improving error handling and observability
  • JEP 531 - Lazy Constants (continued preview): Lets you defer initialization of immutable data until it's actually needed
  • JEP 537 - Vector API (continued incubator): Further enhances high-performance mathematical operations that take advantage of CPU vector capabilities

Taken together, this release balances performance, security, and observability improvements.

Wrap-up

  • Amazon Corretto 27 became GA on September 17, 2026 (Linux / Windows / macOS)
  • Support runs through April 2027
  • G1 is now the default GC everywhere (JEP 523)
  • TLS 1.3 gains post-quantum hybrid key exchange (JEP 527)
  • Compact object headers are on by default (JEP 534)
  • JFR gains in-process data redaction (JEP 536)
  • Pattern matching (JEP 532), structured concurrency (JEP 533), and lazy constants (JEP 531) remain in preview; the Vector API (JEP 537) remains an incubator feature

If you run OpenJDK in production, or just care about GC behavior, memory efficiency, and TLS security, this is a release worth checking out!

Related posts