> Adding more workers because you are blocking on i/o works for low traffic services, not for anything remotely busy. Yes. That just means in very bad cases,

> Adding more workers because you are blocking on i/o works for low traffic services, not for anything remotely busy. Yes. That just means in very bad cases, you can only handle 1 "concurrent request" before performance drops off a cliff. If the third-party service you are talking to is that slow, then you’ll just end up with bufferbloat (high latency in hidden queues) waiting for the service to respond, requests piling up. With async, unless you know what you're doing and handle back pressure, work pile up even worse, the service stops working and you get 0 throughput instead.