JCTools/JCTools

Health v2 · maintenance only

Adoption not part of the score

3877 stars · 597 forks observed · 2026-10-18

What it is AI-extracted, prompt v1, taxonomy v1, 2026-08-29, confidence not recorded

JCTools is a Java library providing high-performance concurrent data structures missing from the JDK, notably lock-free and wait-free queue variants (SPSC/MPSC/SPMC/MPMC) plus non-blocking hash maps and concurrent counters. It is stable and widely used by frameworks such as Netty and RxJava.

Use cases

• pass messages between threads with minimal contention
• replace JDK concurrent queues for higher throughput
• build single-producer single-consumer pipelines
• use lock-free hash maps in concurrent code
• batch drain and fill queue elements efficiently
• benchmark concurrent queue implementations

When to choose

• you need maximum throughput inter-thread message passing on the JVM
• you want specialized SPSC/MPSC/SPMC/MPMC queue semantics
• you need wait-free or lock-free guarantees with bounded or unbounded queues
• you want a battle-tested library used by Netty and RxJava

When to avoid

• your workload is low-contention and JDK queues suffice
• you need distributed or persistent queues rather than in-process ones
• you cannot tolerate sun.misc.Unsafe-based code and are stuck below JDK11

Facets

library · maturity stable

concurrency data-science developer-tools performance jvm lock-free wait-free queues data-structures benchmarks message-passing algorithms

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