Architect a fault-tolerant Feed Generation Engine
Last updated: November 24, 2025
Quick Overview
Design a fault-tolerant feed generation system that handles millions of requests. Discuss trade-offs in consistency, availability, and performance.
Instacart
System Design
Software Engineer
Instacart
November 24, 2025Software Engineer
System Design Round
System Design
Medium
0
12
4,745 solved
Design a fault-tolerant feed generation system that handles millions of requests. Discuss trade-offs in consistency, availability, and performance.
System design interviews at Instacart typically last 45-60 minutes. You are expected to drive the conversation, starting from requirements gathering through to a detailed architecture. The interviewer will evaluate your ability to handle ambiguity and make practical engineering decisions.
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
API design and rate limiting
Requirements gathering and capacity estimation
Message queues and async processing
Load balancing and horizontal scaling
Consistency models and replication
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 handle a 10x increase in traffic overnight?
- How would you implement rate limiting to protect the system?
- How would you handle a region-wide outage?
Practice a Similar Problem on Codemia
Solve a related problem with our interactive workspace, get AI feedback, and view detailed solutions.
Solve on CodemiaSample Answer
Requirements
Functional Requirements
- Feed Generation: Generate personalized product feeds for users based on their preferences and shopping history.
- Real-time Updates: Update feeds in real-time a...
Capacity Estimation
Back-of-Envelope Calculations
- User Base: Assume 10 million active users.
- Requests per User: Each user makes approximately 10 feed requests per day.
- Total Requests: 10 million use...
Submit Your Answer
Markdown supported