I’d also say polling potentially large amount of infrequent sources using one GenServer each with Process.send_after/2 is not the best way. Other than the resource issues, it will also make cancelling and early polling hard to implement. I would use one GenServer that trigger itself every minute and maintain a list of event sources by chronological order. If any polling is due, I can spawn off a process to do the actual work.

Not to nitpick, but when you say pooling you really mean polling, right? It is ok to have typo in a post but it looks like this spelling problem is all over the source. It will become much harder to fix down the road.