1. A method comprising: accepting a job, the job comprising a plurality of phases, each of the phases comprising at least one task; determining, for each of a plurality of slots, a fetching cost associated with receipt of one or more of the tasks; grouping the slots into a plurality of sets; determining a pair of thresholds for each of the sets, the thresholds being associated with the determined fetching costs and comprising upper and lower numerical bounds for guiding receipt of one or more of the tasks.