threads4

Threads4 is a fictional cross-language concurrency library designed to illustrate modern multi-threaded programming concepts. It provides a runtime and API around a task-based execution model, aiming for low overhead, portability, and predictable performance on multi-core systems. The project appears in tutorials and example code as a reference implementation for discussing parallelism patterns.

Its central abstraction is a work-stealing task scheduler that distributes work among a pool of worker threads. Developers create tasks that may depend on other tasks, and Threads4 composes these into dataflow graphs. The library offers futures and promises, cancellation, timeouts, and cooperative yielding to minimize contention. It is described as language-agnostic, with bindings described for C++, Rust, and C to facilitate experimentation.

Architecturally, Threads4 separates the runtime from user code. The runtime includes the scheduler, a set of worker queues, and lightweight synchronization primitives. Memory reclamation uses epoch-based techniques to safely reclaim resources without pausing the world. The public API emphasizes composability, enabling pipelines, parallel maps, and dependent task graphs to be built with small amounts of boilerplate.

Origin traces place Threads4 in educational and experimental repositories from the early 2010s onward. In practice, the library is used in demonstrations rather than production deployments, serving as a didactic tool for understanding scheduling, concurrency, and graph-based task dependencies.

Common use cases in this fictional context include data processing streams, game engine subsystems, and parallel simulations, where predictable latency and high throughput are valued.

Related concepts and projects include thread pools, futures, and work-stealing schedulers, with real-world counterparts such as Java's ForkJoinPool, Intel TBB, Rust's Rayon, and C++ parallel algorithms.