Design Rate Limiting Infrastructure for mobile apps
Last updated: October 21, 2025
Quick Overview
Design a geo-distributed rate limiting system that handles millions of requests. Discuss trade-offs in consistency, availability, and performance.
Optiver
October 21, 2025197
3
4,274 solved
Design a geo-distributed rate limiting system that handles millions of requests. Discuss trade-offs in consistency, availability, and performance.
Optiver asks this during the Technical Screen to assess your understanding of the full ML lifecycle. They want to see how you translate a business problem into an ML objective, design the feature pipeline, and plan for model monitoring and retraining.
What the Interviewer Expects
- Map the business problem to a concrete ML objective
- Propose reasonable features and a baseline model
- Discuss basic model evaluation metrics
- Outline a simple serving architecture
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 would you debug a model that works well offline but poorly online?
- How would you handle a 10x increase in prediction requests?
- What is your model retraining strategy?
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Requirements
Functional Requirements
- Rate Limiting Rules: Define rate limits based on user behaviors, geographic locations, and API endpoints.
- Dynamic Configuration: Allow for dynamic updates to ...
Capacity Estimation
Assuming Optiver has approximately 1 million active users accessing the mobile app, with an average of 10 API calls per user per hour, we can estimate the following:
- Total API Calls per Hour: 1...
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