System designHardsd-g634

Subject CoordinationLevel Senior–Staff~50 minCommon in Concurrency interviewsIndustries Technology, Software development

Question

Design a workflow/saga orchestrator that executes multi-step business transactions (e.g. travel booking: reserve flight, hotel, car) where some steps run concurrently and any failure must trigger compensating actions to undo completed steps. Constraints: ~5k workflows/sec, steps call external services with their own timeouts, the orchestrator may crash mid-workflow, and the same workflow must not double-execute a step. Describe state tracking, how concurrent branches are coordinated and joined, and the failure/compensation model.

What a strong answer looks like

Clarify scale and constraints first. Propose a clean component breakdown, then go deep on the hard parts — data model, bottlenecks, consistency, failure modes — and name the trade-offs you are making.

Learn the concepts

Narrate your design

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Run or narrate your approach, then ask the coach.