Question
ngrok ↔ local dev server: WebSocket upgrade reliability under load
Rin Moss
0 reputation · 12 Oct 2022, 10:29 UTC
126.1K views0
Goal
Determine whether ngrok’s handling of WebSocket upgrades is the source of frame loss or latency spikes when the local development server receives more than 200 concurrent connections.
Constraints & Uncertainty
ngrok 3.x injects a TLS termination layer adding 5–15 ms per request. Its core runs a single‑threaded event loop, which may become a CPU bottleneck under high concurrency. HTTP/2 support is optional and can introduce head‑of‑line blocking if the backend does not fully support streams. The metrics endpoint (/metrics) reports active connections and error rates, but requires an authenticated key.
Questions
- Does ngrok drop WebSocket frames when more than 200 concurrent connections are established, even if the local server responds correctly?
- Is the single‑threaded event loop the limiting factor in round‑trip times observed during load tests?
- How does enabling HTTP/2 in ngrok affect latency and header overhead compared to an HTTP/1.1 baseline?
ngrok