alibaba/transmittable-thread-local

Health v2 · maintenance only

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8293 stars · 1722 forks observed · 2026-08-28

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

TransmittableThreadLocal (TTL) is a zero-dependency Java library providing an enhanced InheritableThreadLocal that transmits context values between threads even when thread pools reuse threads. It includes a Java Agent to transparently instrument JDK thread pool implementations like ExecutorService and ForkJoinPool.

Use cases

• pass request context through thread pools in Java middleware
• propagate trace IDs across async tasks for distributed tracing
• transmit ThreadLocal values when using ExecutorService or ForkJoinPool
• maintain user session context in pooled threads
• build APM or tracing frameworks that need async context propagation
• wrap Runnable and Callable to carry context across thread boundaries

When to choose

• your Java framework or middleware needs context propagation through pooled threads
• InheritableThreadLocal fails because threads are reused from a pool
• you want a simple, zero-dependency solution with optional Java Agent instrumentation
• you're building distributed tracing or APM tooling on the JVM

When to avoid

• you don't use thread pools or async execution
• you're on a non-JVM platform
• you need coroutine or reactive-stream context propagation instead of thread-based

Facets

library · maturity stable

concurrency middleware tracing developer-tools developer-tools microservices backend monitoring jvm threadlocal thread-pool context-propagation async executor java-agent zero-dependency

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