# Dynamic feeder population during simulation

**URL:** <https://community.gatling.io/t/dynamic-feeder-population-during-simulation/8624>\
**Category:** Gatling (Open-Source)\
**Created:** [January 12, 2024, 3:10pm UTC](https://community.gatling.io/t/dynamic-feeder-population-during-simulation/8624 "2024-01-12T15:10:21Z")\
**Posts on this page:** 1\
**Showing post:** 2

<div class="post-metadata">

**Author:** ![sbrevet](https://dub1.discourse-cdn.com/flex013/user_avatar/community.gatling.io/sbrevet/32/830_2.png) [@sbrevet](https://community.gatling.io/u/sbrevet)\
**Post date:** [January 12, 2024, 3:22pm UTC](https://community.gatling.io/t/dynamic-feeder-population-during-simulation/8624/2 "2024-01-12T15:22:25Z")

</div>

Hi @Vadam,

As explained in the first part of the [Feeder](https://docs.gatling.io/gatling/reference/current/core/session/feeder/) documentation, `Feeder` is merely a rebrand of an `Iterator<Map<String, Object>>`.  
So you may implement one yourself.

For your specific use case, you may want that such an implementation rely on a global variable shared by your current scenario and another scenario that refresh the token when needed.  
In your “user” scenario, before each request that requires this token, you may want to feed it (to be sure to be up to date).

In the other hand, it means that your tokens are not linked to a user, so maybe manipulating directly the global variable may be more suitable.  
Did you read [the topic about that and the wonderful implementation by @GeMi](https://community.gatling.io/t/token-refresh-java-example/7935)?

Cheers!

---

_[View the full topic](https://community.gatling.io/t/dynamic-feeder-population-during-simulation/8624)._