Design a distributed job scheduler
Company: Meta
Role: Software Engineer
Category: System Design
Difficulty: medium
Interview Round: Onsite
Design a distributed job scheduler that can run recurring and one-off jobs.
Requirements:
- Users define jobs with schedule (cron) or immediate run.
- Execute jobs on a worker fleet.
- Retries with backoff; dead-letter queue.
- At-least-once execution; optional exactly-once for some jobs.
- Provide job status, logs, and history.
Out of scope: full workflow DAG engine (Airflow).
Quick Answer: This English summary evaluates a candidate's competency in designing reliable, scalable distributed systems for job scheduling and execution, encompassing scheduling semantics, worker orchestration, retry and dead-letter handling, and execution guarantees.