Locust.io: Controlling the request per second parameter

Question

I have been trying to load test my API server using Locust.io on EC2 compute optimized instances. It provides an easy-to-configure option for setting the consecutive

Answer 1

(one of the Locust authors here)

First, why do you want to control the RPS? One of the core ideas behind Locust is to describe user behavior and let that generate load (requests in your case). The question Locust is designed to answer is: How many concurrent users can my application support?

I know it is tempting to go after a certain RPS number and sometimes I "cheat" as well by striving for an arbitrary RPS number.

But to answer your question, are you sure your Locusts doesn't end up in a dead lock? As in, they complete a certain number of requests and then become idle because they have no other task to perform? Hard to tell what's happening without seeing the test code.

Distributed mode is recommended for larger production setups and most real-world load tests I've run have been on multiple but smaller instances. But it shouldn't matter if you are not maxing out the CPU. Are you sure you are not saturating a single CPU core? Not sure what OS you are running but if Linux, what is your load value?