Design concurrency-safe shared payment account API
TeslaSoftware Engineer · Technical Screen
Last updated
Design concurrency-safe shared payment account API evaluates requirements, scale assumptions, API/data design, architecture, trade-offs, failure modes, and rollout in a realistic interview setting. A strong answer states assumptions, handles edge cases, explains trade-offs, and shows how to validate the result clearly.
Scenario: Two users share one online payment account and submit payments at the same time. From an API and real-world engineering perspective, how would you ensure the balance remains correct and prevent double-spending? Specify request/response design, idempotency keys, concurrency control (e.g., optimistic or pessimistic locking, transactions), consistency guarantees, retries, and monitoring. Additionally, how would you scale the service to handle very high concurrency and massive request volumes?
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