TL;DR
Three-sided marketplaces face challenges in optimizing dispatch decisions due to delayed feedback on operational outcomes. A reinforcement learning system was developed at DoorDash to adapt dispatch objective weights using delayed signals, employing a store-level policy that selects multipliers for the dispatch optimizer.
✦ Why It Matters
Engineers can leverage delayed feedback in reinforcement learning to optimize decision-making in complex marketplaces.
Key Takeaways
Full Summary
Three-sided marketplaces, like food delivery services, struggle with optimizing dispatch decisions because feedback on performance, such as delivery speed and courier utilization, often arrives late. To address this, a reinforcement learning system was implemented at DoorDash that adapts the weights of dispatch objectives based on delayed marketplace feedback.
Instead of overhauling the existing combinatorial assignment optimizer, a store-level policy was created to select discrete multipliers that adjust the tradeoff between delivery quality and batching efficiency. The methodology involved training a shared value function using centralized offline data and decentralized execution, incorporating Double Q-learning targets and a conservative regularizer to mitigate value overestimation.
In a production switchback experiment, the offline-trained policy led to a significant increase in batching and a reduction in courier-side time costs, all while preserving customer-facing delivery quality. These findings demonstrate the potential of using real-world feedback to safely adapt decision-making policies in complex systems.
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