Increasing the request rate

Increase the number of requests per second using a combination of the following steps:

  1. Increase the number of users. To fully utilize your target system you may need a lot of simultaneous users, especially if each request takes a long time to complete.

  2. If response times are unexpectedly high and/or increasing as the number of users go up, then you have probably saturated the system you are testing and need to dig into why. This is not really a Locust problem, but here are some things you may want to check:

    • resource utilization (e.g. CPU, memory & network. Check these metrics on the locust side as well)

    • configuration (e.g. max threads for your web server)

    • back end response times (e.g. DB)

    • client side DNS performance/flood protection (Locust will normally make at least one DNS Request per User)

  3. If Locust prints a warning about high CPU usage (WARNING/root: CPU usage above 90%! ...) try the following:

    • Run Locust distributed to utilize multiple cores & multiple machines

    • Try switching to FastHttpUser to reduce CPU usage

    • Check to see that there are no strange/infinite loops in your code

  4. If you are using a custom client (not HttpUser or FastHttpUser), make sure any client library you are using is gevent-friendly otherwise it will block the entire Python process (essentially limiting you to one user per worker)


Hatch rate/ramp up does not change peak load, it only changes how fast you get there.