Design a distributed cron scheduler

Q: Design a distributed cron scheduler

This question evaluates expertise in distributed system design, focusing on scheduling, coordination (leader election and leases), time correctness (clock skew, time zones, DST), fault tolerance, scalability, delivery semantics, and operational resilience for executing jobs across a fleet.

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Question

System Design: Distributed Cron Scheduler

Context

Design a distributed cron scheduler that executes scheduled jobs across a fleet of machines. The system must be highly available, horizontally scalable, and free of single points of failure. It should robustly handle time-related edge cases, failures, and operational workflows.

Requirements

Availability and scalability
- No single point of failure
- Horizontal scale-out of both scheduling and execution
Coordination
- Leader election and lease management
Time correctness
- Tolerance to clock skew
- Support for time zones and DST transitions
Scheduling robustness
- Misfire detection and catch-up policy
Delivery semantics
- Retries and idempotency
- Discuss at-least-once vs exactly-once
Flow control and resilience
- Backpressure
- Worker crash recovery
Architecture details
- Data model
- Coordination mechanism
- Job placement/sharding
- Failure detection
- Monitoring/alerting
- Rollout/rollback strategy
Alternatives and trade-offs
- Compare database-based scheduling, coordination via ZooKeeper/etcd, and message-queue-centric designs

Provide a clear end-to-end design, with justifications and trade-offs.

Design a distributed cron scheduler

System Design: Distributed Cron Scheduler

Context

Requirements

Solution

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Design a distributed cron scheduler

Overview

System Design: Distributed Cron Scheduler

Context

Requirements

Solution

Comments (0)