Design a Task Scheduling Service
Last updated: June 1, 2026
Quick Overview
Design a low-latency task scheduling system that handles millions of requests. Discuss trade-offs in consistency, availability, and performance.
TikTok
June 1, 2026175
13
2,552 solved
Design a low-latency task scheduling system that handles millions of requests. Discuss trade-offs in consistency, availability, and performance.
TikTok asks this during the Onsite to assess your architectural thinking. They want to see how you decompose a complex problem, choose appropriate technologies, and reason about failure modes. Strong candidates proactively discuss monitoring, alerting, and operational concerns.
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
- What would the deployment pipeline look like for this system?
- How would you migrate from a monolithic to a microservices architecture?
- What monitoring and alerting would you set up on day one?
- How do you ensure data consistency across multiple services?
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Requirements
Functional Requirements
- Task Creation: Users can schedule new tasks with a specified execution time and priority.
- Task Management: Users can view, modify, or cancel scheduled tasks. ...
Capacity Estimation
To estimate capacity, assume TikTok has 1 billion active users, with each user scheduling an average of 2 tasks per day.
Calculations:
- Total Daily Tasks: 1 billion users * 2 tasks/user = 2...
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