Build a real-time Load Balancing Pipeline
Last updated: March 7, 2026
Quick Overview
Design a real-time load balancing system that handles millions of requests. Discuss trade-offs in consistency, availability, and performance.
Instacart
March 7, 20265
12
2,736 solved
Design a real-time load balancing system that handles millions of requests. Discuss trade-offs in consistency, availability, and performance.
Instacart asks this during the Technical Screen 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
- Clearly define functional and non-functional requirements
- Propose a reasonable high-level architecture with core components
- Choose appropriate data storage solutions with basic justification
- Discuss basic scaling strategies (horizontal scaling, caching)
- Identify potential bottlenecks and suggest simple solutions
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 migrate from a monolithic to a microservices architecture?
- How would you optimize costs as the system scales?
- How would you handle a region-wide outage?
- How do you ensure data consistency across multiple services?
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Capacity Estimation
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