Abstract: An online concierge system generates order batches for pickers and offers those order batches. The online concierge system generates a set of candidate order batches, which are subsets of a received set of orders. The online concierge system generates a set of order batch scores for each of a set of candidate pickers, and offers the candidate order batches to the candidate pickers for the candidate pickers to service based on the set of order batch scores. If a candidate picker accepts the offered order batch, the online concierge system identifies candidate order batches with overlapping orders with the order batch accepted by the candidate picker, and rescinds the offer for each of the candidate pickers to service the order batches.

Abstract: An online concierge system receives information describing orders from its customers and generates a route for each order based on this information. The routes are partitioned into multiple sets of routes and multiple candidate generation processes are executed in parallel. During execution of a candidate generation process, one or more routes included in each set of routes are paired with shoppers of the system based on a set of constraints, producing multiple route-shopper pairs. A cost associated with each route-shopper pair is determined based on attributes associated with each shopper and/or information associated with each route of the pair. During an optimization process, which is executed asynchronously with the candidate generation process, one or more route-shopper pairs are selected based on pairing-cost data identifying route-shopper pairs and their associated costs. One or more requests to fulfill orders are sent to one or more shoppers based on the selected route-shopper pair(s).