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Handle payment-service outages

DoorDashSoftware Engineer · Onsite
EasySoftware EngineerOnsiteSoftware Engineering Fundamentals

Last updated

This question evaluates a candidate's competence in designing fault-tolerant payment workflows and operational resilience, covering concepts such as idempotency, retry strategies, queuing and dead-letter handling, circuit breaking, reconciliation, and monitoring.

You own a service that computes courier payouts and then submits payout requests to a downstream payment processor. What should your system do if the payment service is temporarily unavailable, timing out, or returning intermittent errors?

Discuss how to preserve correctness and a good user experience, including:

  • idempotency for payout requests
  • retries with exponential backoff and jitter
  • when to retry synchronously vs. asynchronously
  • circuit breaking and fallback behavior
  • queue-based recovery and dead-letter handling
  • reconciliation after the payment service recovers
  • monitoring and alerting