@kvnvelasco know this is your thread, but, since it's fresh in your mind, any chance you'd mind explaining how the executor you use works? Have been trying to understand how FuturesUnordered manages tasks. Full unresolved thread here, but basically trying to understand how the linked list works with ready_to_run_queue. Only asking since much of the complexity is in ready_to_run_queue which you seem to understand from above. Thanks @alice for the link