I suspect that you aren’t sharing some assumptions that you are making here. If you don’t need a reply - how are you planning to save information back to the database? Now it could work if you plan to use Ecto, as it is an independent OTP application that handles all DB requests concurrently. However even then ideally you should restructure your processing to fetch as much data upfront to avoid each separate process repeatedly hammering the database.
This topic may help you to get a better feel for all things Task, and GenServer:
https://elixirforum.com/t/sasa-jurics-beyond-task-async-blog/6107
If you need the capability to throttle processing then as already suggested GenStage is worth considering. Typically you would organize processing a bit differently - rather than having a Task process an “element” end-to-end you set up a processing pipeline were each stage does just one (short) phase of the work before it sending it the the next stage which which does the next (short) phase of the work - etc.
