threadtothread

Thread-to-thread, or threadtothread, denotes a pattern in concurrent programming in which two threads exchange information directly without routing messages through a separate process or central broker. This direct communication can occur within a single process or across process boundaries when supported by shared memory or inter-process communication primitives. The term is used to describe both low latency handoffs and rendezvous-style exchanges where one thread sends data and the other acknowledges receipt in a tightly coupled sequence.

Common implementations rely on shared memory regions paired with synchronization primitives such as mutexes and condition variables, or on lock-free data structures like ring buffers and atomic operations. Cross-process variants may use memory-mapped files or dedicated IPC channels configured for direct handoff. Some languages offer built-in support: for example, certain libraries provide rendezvous channels or synchronous queues that implement threadtothread semantics.

Advantages include reduced latency, lower overhead from avoiding middlemen, and greater predictability in timing. Disadvantages include increased risk of data races and deadlocks, tighter coupling between threads, and greater complexity in correctness guarantees including memory visibility and ordering.

Common use cases include real-time data processing between producer and consumer threads, tight control loops in multimedia or gaming, and high-performance pipelines where micro-batching is feasible. Design considerations include choosing synchronization style (blocking vs. non-blocking), memory visibility guarantees, and ensuring graceful degradation if a thread stalls.

Relation to related concepts include inter-thread communication, shared memory, lock-free programming, producer-consumer patterns, and rendezvous channels. See also thread synchronization and concurrent data structures.