I started with a single-node scheduler and worked outward from there, which in hindsight was probably the right move but I spent too long on it before the interviewer nudged me toward fault tolerance.
Start by clarifying requirements and constraints, then propose a high-level architecture that separates scheduling, execution, and state management. Dive into key components like distributed queues, leader election, and fault tolerance, and discuss trade-offs between consistency, availability, and scalability.
Pro tip: Emphasize idempotency and at-least-once execution semantics to handle failures gracefully, and mention how you would monitor and alert on job failures and delays.
Ask about scale, job types, latency, durability, and failure handling to scope the design appropriately.
Outline components: job submission API, scheduler, distributed queue, workers, and a metadata store for job states.
Choose a scheduling strategy (e.g., priority queues, fair scheduling) and explain how to assign jobs to workers.
Describe how to handle worker failures, duplicate jobs, and ensure exactly-once or at-least-once semantics.
Discuss horizontal scaling, partitioning, and metrics for observability and alerting.
AI-generated suggestions, not part of the candidate's original notes. May be inaccurate — verify before relying on them.