Architect a high-throughput Messaging Engine
Last updated: December 21, 2025
Quick Overview
Design a high-throughput messaging system that handles millions of requests. Discuss trade-offs in consistency, availability, and performance.
Dropbox
December 21, 2025116
7
4,678 solved
Design a high-throughput messaging system that handles millions of requests. Discuss trade-offs in consistency, availability, and performance.
Dropbox asks this during the Onsite 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
- What is your model retraining strategy?
- How would you handle the cold start problem?
- What would you do if model performance degrades over time?
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Requirements
Functional Requirements:
- High Throughput: The system should handle millions of messages per second with minimal latency.
- Message Delivery Guarantees: Ensure at-least-once delivery of...
Capacity Estimation
Assuming Dropbox handles approximately 100 million users, with an average of 10 messages sent per user per day, the estimated daily message volume would be:
- Total Messages per Day: 100 million ...
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