As discussed in other topics, current behavior of
stale-while-revalidate seems to be unexpected to users including me.
This document says first request after max-age will be used to revalidate:
Indicates that it is fresh for 600 seconds, and it may continue to be served stale for up to an additional 30 seconds to parallel requests for the same resource while the initial synchronous revalidation is attempted.
but, I’d like to get stale response by the first request. As I see, this will be the common understanding of what stale-while-revalidate does.