portswhile

Portswhile is a coined term used in computer networking and systems programming to describe a port-centric event-driven pattern in which a server monitors multiple network ports using I/O multiplexing and processes activity within a persistent loop. The name blends 'port' (network port) with 'while' (the looping construct that governs the main processing cycle). There is no formal standard for portswhile; it appears mainly in informal discussions and blog posts as a descriptive label for a reactor-like approach focused on port readiness.

Definition and mechanism: In a portswhile implementation, a server registers a set of ports with an I/O multiplexer (such as select, poll, epoll, or kqueue). The main thread enters a while loop that runs while a condition, such as server_running, remains true. The multiplexer reports which ports are ready, and the loop dispatches appropriate handlers (accepting connections, reading or writing data) before rechecking readiness. Versions may be single-threaded or multi-threaded and may vary in whether the loop blocks or uses edge-triggered events.

Relation to other patterns: Portswhile overlaps with the reactor pattern and other asynchronous I/O approaches. Its distinguishing emphasis is per-port demultiplexing within the central loop. Practical deployments include high-concurrency proxies, gateways, and lightweight microservice front-ends. Implementations typically require careful non-blocking I/O, proper error handling, and consideration of backpressure.

Limitations and reception: Critics note that portswhile can become complex and fragile if not structured carefully, especially when mixing blocking calls inside handlers. It is not widely standardized, and alternative patterns such as asynchronous frameworks and the explicit reactor pattern are commonly recommended. See also: event-driven programming, I/O multiplexing, reactor pattern, select, poll, epoll, kqueue.