Design a Cron Job Scheduler
Company: Snowflake
Role: Software Engineer
Category: System Design
Difficulty: medium
Interview Round: Technical Screen
Design a job scheduler service with effectively unlimited worker capacity.
The system must support:
- Recurring jobs defined by cron-style schedules
- `pause(job_id)`: stop scheduling new runs for that job, but allow already running executions to finish
- `resume(job_id)`: allow future scheduled runs to continue
Describe the API design, data model, scheduler logic, execution flow, and how to make the system reliable under crashes or multiple scheduler instances.
Quick Answer: This question evaluates a candidate's ability to design a scalable, distributed job scheduler, encompassing API and data model design, cron-style recurrence, pause/resume semantics, concurrency control, and fault-tolerant execution.