How does asynchronous request processing work in Spring MVC?

I choose async MVC when a specific Servlet endpoint benefits from deferred completion without requiring an end-to-end reactive stack. Capacity remains bounded by delegated workers, memory held per open response, and downstream limits. I test timeout races, completion after timeout, cancellation, shutdown, and duplicate callbacks because those paths expose ownership bugs. Metrics separate active async requests, executor queue delay, completion latency, timeout, and work continuing after the caller has left.