Yunohost Apache MaxRequestWorkers: Diagnosing latency spikes under concurrent load

Goal

Determine whether the default MaxRequestWorkers setting is a bottleneck when Yunohost handles many simultaneous web requests.

Constraints

• Yunohost installs Apache with MaxRequestWorkers=150 by default.
• The bundled PHP‑FPM pool is configured with 5 workers (pm.max_children).
• Increasing worker counts raises memory consumption, risking swap.
• No automatic tuning based on system resources.

Unresolved Decision

It is unclear whether raising MaxRequestWorkers, pm.max_children, or both will reduce latency without causing resource exhaustion.

Questions

• What is the maximum safe value for MaxRequestWorkers on a 4 GB RAM Yunohost server?
• Should pm.max_children be scaled proportionally when MaxRequestWorkers is increased?
• Will raising MaxRequestWorkers alone lead to swapping if PHP‑FPM remains at 5 workers?