Design a Image Processing Service
Last updated: April 7, 2026
Quick Overview
Design a scalable image processing system that handles millions of requests. Discuss trade-offs in consistency, availability, and performance.
Expedia
System Design
Software Engineer
Expedia
April 7, 2026Software Engineer
Technical Screen
System Design
Easy
10
7
1,213 solved
Design a scalable image processing system that handles millions of requests. Discuss trade-offs in consistency, availability, and performance.
Expedia 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
A/B testing and experimentation
Training pipeline and infrastructure
Feature engineering and feature stores
Model serving and latency optimization
Feedback loops and model retraining
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 ensure fairness and reduce bias in the model?
- What is your model retraining strategy?
- How would you handle the cold start problem?
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Requirements
- Functional Requirements:
- The system must process images uploaded by users (e.g., hotel photos, user-generated content).
- It should perform operations such as resizing, format conversion, ...
Capacity Estimation
To estimate capacity, we consider:
- Daily Requests: 10 million requests per day
- Requests per Second (RPS): 10 million requests / 86400 seconds = ~115.7 RPS
- Image Size: Assuming an ave...
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