reading the documentation of limitRate method from Reactor https://projectreactor.io/docs/core/release/api/reactor/core/publisher/Flux.html#limitRate-int- and testing with StepVerifier is not actually limiting the number of events flowing from upstream to downstream. As mentioned here https://inspired-it.nl/2022/03/21/how-does-limitrate-work-in-reactor/, is about limiting the number of requests to upstream and to gain performance because we reduce the number of calling the request method from reactor. So:

I’m using WebClient from reactor-netty to call the downstream,
the downstream with latency is 15s to the response.
I’m trying to use Jmetter to send 20request per second, and half of them return 500 with WebClient timeout exception like below: