openjdk/loom

Health v2 · maintenance only

Flags: no_releases

Adoption not part of the score

2014 stars · 255 forks observed · 2026-08-28

What it is AI-extracted, prompt v1, taxonomy v1, 2026-08-30, confidence not recorded

Project Loom is the OpenJDK project that developed lightweight concurrency for the Java platform, most notably virtual threads (fibers) and structured concurrency. This repository is a JDK development fork where the Loom features were implemented before being integrated into mainline OpenJDK releases.

Use cases

• run millions of lightweight concurrent tasks in Java
• write blocking-style code that scales like async
• adopt virtual threads for high-throughput servers
• use structured concurrency to manage task lifetimes
• migrate thread-per-request Java services without reactive complexity
• experiment with continuations on the JVM

When to choose

• you need massive concurrency in Java without rewriting to async/reactive styles
• you want to test or contribute to JVM-level virtual thread development
• your server handles many concurrent blocking I/O operations

When to avoid

• you need a stable production JDK - use a mainline OpenJDK release instead
• you work in a non-JVM language
• you need CPU-bound parallelism only - traditional thread pools suffice

Facets

library · maturity active

concurrency interpreter developer-tools programming-languages developer-tools microservices jvm windows virtual-threads jvm openjdk project-loom lightweight-concurrency continuations linux macos

Member repositories

For agents

markdown · JSON · MCP: product_card(name="openjdk/loom")