An Asynchronous, Non-Blocking Framework for Next-Generation Edge API Gateways: Formal Design and Empirical Evaluation

The thread-per-request model's concurrency ceiling is not a theoretical concern — it manifests as latency collapse the moment an edge node saturates its OS thread pool. On constrained hardware with 2–8 cores and 4–16 GB of RAM, that ceiling arrives far sooner than in a data center, and no amount of pool tuning recovers throughput once you hit it. We built an asynchronous, non-blocking gateway framework around an event-driven I/O model, a lock-free request pipeline, and a back-pressure-aware routing layer, then measured it against an Apache mpm_prefork synchronous baseline on a commodity i5-1235U edge node. Peak sustainable throughput capacity reached 112,400 req/s — 3.8× the baseline's peak capacity of 29,600 req/s — with P99 latency falling from 69 ms to 18 ms at 80% offered load and CPU utilization dropping by 31% at equivalent offered load (range: 29–33% across five runs). Back-pressure propagation from an overloaded upstream to client-visible flow control ran a median of 4.2 ms (IQR: 3.8–4.9 ms). M/M/c queuing bounds for throughput, queuing delay, and resource utilization were derived before benchmarking; measurements stayed within 5% of model predictions for ρ ≤ 0.8 under stable load. At edge scale, async design is the baseline requirement for sustaining cloud-native connection counts.