# How to correct user injection? **URL:** \ **Category:** Gatling (Open-Source)\ **Created:** [June 10, 2022, 2:26pm UTC](https://community.gatling.io/t/how-to-correct-user-injection/6839 "2022-06-10T14:26:38Z")\ **Posts on this page:** 4\ **Page:** 1
**Author:** ![Dmytro](https://avatars.discourse-cdn.com/v4/letter/d/9fc348/32.png) [@Dmytro](https://community.gatling.io/u/Dmytro)\ **Post date:** [June 10, 2022, 2:26pm UTC](https://community.gatling.io/t/how-to-correct-user-injection/6839/1 "2022-06-10T14:26:39Z")
Hello everyone, I’m not that proficient with user injections so I would like to ask for some help. We have a scenario by which users should be injected: 30 minutes - stable load, then 30 minutes of spike with a big number of users and that repeats again. ```auto setUp(TestScenario.scenario .injectOpen( constantUsersPerSec(ConfigHelper.USERS_PER_SECOND).during(Duration.ofMinutes(ConfigHelper.CONSTANT_USER_RATE_DURATION)), stressPeakUsers(ConfigHelper.SPIKE_USERS_NUMBER).during(Duration.ofMinutes(ConfigHelper.SPIKE_DURATION)), constantUsersPerSec(ConfigHelper.USERS_PER_SECOND).during(Duration.ofMinutes(ConfigHelper.CONSTANT_USER_RATE_DURATION)), stressPeakUsers(ConfigHelper.SPIKE_USERS_NUMBER).during(Duration.ofMinutes(ConfigHelper.SPIKE_DURATION)), constantUsersPerSec(ConfigHelper.USERS_PER_SECOND).during(Duration.ofMinutes(ConfigHelper.CONSTANT_USER_RATE_DURATION)) ) ).maxDuration(Duration.ofMinutes(ConfigHelper.DURATION)) .protocols(ConfigHelper.httpProtocol) .assertions(global().successfulRequests().percent().gt(ConfigHelper.SUCCESS_RATE)); ``` We have executed this code with parameters such as: Users per second: 15 Constant user rate duration: 30 Spike users number: 400 Spike duration: 30 Test Duration: 150 But numbers of users were not like a would expect: ![Screenshot from 2022-06-10 17-24-44](https://europe1.discourse-cdn.com/flex013/uploads/gatling2/original/1X/e09cc7e794b22317828a5a1abe91498069f8ae2d.png) I wanted to create a quite opposite picture from the one that I provided. Like 200 or so users during constant rate and big spike with 400 users during the spike. So, I would like to have some guidance, thank you in advance 😄 ---
**Author:** ![slandelle](https://dub1.discourse-cdn.com/flex013/user_avatar/community.gatling.io/slandelle/32/4_2.png) [@slandelle](https://community.gatling.io/u/slandelle)\ **Post date:** [June 10, 2022, 3:45pm UTC](https://community.gatling.io/t/how-to-correct-user-injection/6839/2 "2022-06-10T15:45:23Z")
You misunderstand `stressPeakUsers`. Quoting the [documentation](https://gatling.io/docs/gatling/reference/current/core/injection/#open-model): > Injects a given number of users following a smooth approximation of the [heaviside step function](http://en.wikipedia.org/wiki/Heaviside_step_function) stretched to a given duration. With your values, each peak will inject a **total** of 400 users. Over 30 minutes, that’s merely ~1 every 5 seconds. ---
**Author:** ![Dmytro](https://avatars.discourse-cdn.com/v4/letter/d/9fc348/32.png) [@Dmytro](https://community.gatling.io/u/Dmytro)\ **Post date:** [June 12, 2022, 10:34am UTC](https://community.gatling.io/t/how-to-correct-user-injection/6839/3 "2022-06-12T10:34:11Z")
Oh, so I was wondering why is it happening…would you suggest something different so that I can use it to simulate the scenario that we want? Or do we just need to increase the number of users? ---
**Author:** ![slandelle](https://dub1.discourse-cdn.com/flex013/user_avatar/community.gatling.io/slandelle/32/4_2.png) [@slandelle](https://community.gatling.io/u/slandelle)\ **Post date:** [June 12, 2022, 11:55am UTC](https://community.gatling.io/t/how-to-correct-user-injection/6839/4 "2022-06-12T11:55:54Z")
Just increase the number of users. A 30 min spike is really not a spike:slight\_smile: