Design cron scheduler and reward/review system

Q: Design cron scheduler and reward/review system

This is a System Design interview question from DoorDash for Software Engineer roles. View the full question and solution on PracHub.

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Question

System Design: Company-Wide Scheduler Platform and Employee Review & Rewards System

You are designing two platforms for a fast-growing, multi-tenant technology company. Address each part independently, but note any shared building blocks if relevant.

Part A — Company-Wide Scheduled Job Platform (Cron-like)

Design a horizontally scalable platform to run scheduled workflows across services.

Include:

Scheduling and execution
- Schedule management: crontab expressions, calendar/holiday exceptions, and time zones (DST-safe)
- Workflow DAGs and task dependencies
- Retries with exponential backoff and idempotency guarantees
- Backfills for missed/retroactive runs
- Concurrency control: global, per-tenant, per-workflow limits
- Access control and multi-tenant isolation
Reliability and operations
- Observability: logs, metrics, traces; failure alerting
- Horizontal scalability: sharding and stateless workers
- Storage schemas for schedules, DAGs, runs, leases/locks, and audit
- Coordinator/worker architecture: leader election, queues, heartbeats
- Disaster recovery and operational runbooks

Discuss trade-offs (e.g., at-least-once vs exactly-once), and provide concrete storage schemas and component interactions.

Part B — Employee Review & Rewards System

Design a system that supports performance reviews and employee rewards with strong privacy and compliance.

Include:

Core features
- Performance review cycles (self/manager/peer), calibration, and peer feedback
- Reward points/grants, redemption, policies, and approval workflows
- Privacy/visibility controls and audit trails
Architecture and integrations
- Service boundaries and data models
- Integrations with HRIS (org, titles, managers), SSO, and payroll/stock systems
- Abuse/fraud prevention, rate-limiting, and anomaly detection
Operations
- Observability, SLAs, and disaster recovery
- Data retention, legal holds, and regional data residency

Provide data schemas, state machines, and key workflows. Call out edge cases, safeguards, and scale assumptions.

Design cron scheduler and reward/review system

System Design: Company-Wide Scheduler Platform and Employee Review & Rewards System

Part A — Company-Wide Scheduled Job Platform (Cron-like)

Part B — Employee Review & Rewards System

Solution

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