> The rule I used for deciding on what the optimal number of worker processes was is simple: for each framework I started at a single worker and increased the worker count successively until performance got worse.
> The optimal number of workers varies between async and sync frameworks and the reasons are straightforward. Async frameworks, due to their IO concurrency, are able to saturate a single CPU with a single worker process.
> The same is not true of sync workers: when they do IO they will block until the IO is finished. Consequently they need to have enough workers to ensure that all CPU cores are always in full use when under load.
> Why the worker count varies
> The rule I used for deciding on what the optimal number of worker processes was is simple: for each framework I started at a single worker and increased the worker count successively until performance got worse.
> The optimal number of workers varies between async and sync frameworks and the reasons are straightforward. Async frameworks, due to their IO concurrency, are able to saturate a single CPU with a single worker process.
> The same is not true of sync workers: when they do IO they will block until the IO is finished. Consequently they need to have enough workers to ensure that all CPU cores are always in full use when under load.