Design a Task Scheduling Service
Last updated: September 14, 2025
Quick Overview
Design a high-throughput task scheduling system that handles millions of requests. Discuss trade-offs in consistency, availability, and performance.
Zillow
September 14, 2025148
12
1,069 solved
Design a high-throughput task scheduling system that handles millions of requests. Discuss trade-offs in consistency, availability, and performance.
This is a common system design question asked during Technical Screen at Zillow. The interviewer expects you to demonstrate your ability to design large-scale distributed systems, make well-reasoned trade-offs, and communicate your thought process clearly. Zillow values engineers who can think about scalability from day one.
What the Interviewer Expects
- Systematically gather requirements and estimate capacity (QPS, storage, bandwidth)
- Design a scalable architecture with clear component responsibilities
- Make well-reasoned database and caching decisions with trade-off analysis
- Address consistency vs availability trade-offs specific to the use case
- Discuss partitioning strategy, replication, and data modeling
- Cover failure handling, monitoring, and alerting strategies
Key Topics to Cover
How to Approach This
- Start by clarifying functional and non-functional requirements with the interviewer.
- Estimate the scale: QPS, storage, bandwidth. This drives your design decisions.
- Draw a high-level architecture first, then deep dive into 1-2 critical components.
- Discuss trade-offs explicitly (e.g., consistency vs availability, SQL vs NoSQL).
- Address failure scenarios, monitoring, and how the system handles 10x traffic spikes.
Possible Follow-up Questions
- How do you ensure data consistency across multiple services?
- How would you implement rate limiting to protect the system?
- How would you handle a region-wide outage?
- How would you handle schema migrations with zero downtime?
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Requirements
- Functional Requirements:
- Ability to schedule, execute, and monitor tasks (e.g., data processing, notifications).
- Support for recurring tasks (daily, weekly, etc.).
- Provide an API for...
Capacity Estimation
- Estimating QPS: Assume Zillow handles 100 million requests per day, which translates to approximately 1,157 requests per second (QPS).
- Storage Requirements: If each task requires 1 KB of s...
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