Design a fault-tolerant Messaging System
Last updated: August 25, 2025
Quick Overview
Design a fault-tolerant messaging system handling millions of requests. Discuss consistency, availability, and performance trade-offs.
Walmart
System Design
Software Engineer
Walmart
August 25, 2025Software Engineer
System Design Round
System Design
Medium
752
5
4,454 solved
Design a fault-tolerant messaging system handling millions of requests. Discuss consistency, availability, and performance trade-offs.
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.
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Practice System Design ProblemsSample Answer
Requirements
Functional Requirements:
- Message Sending: Users must be able to send messages in real-time.
- Message Receiving: Users must receive messages instantly or with minimal delay.
- **Messa...
Capacity Estimation
Assuming Walmart has approximately 250 million active users, and each user sends an average of 10 messages per day:
- Total messages per day = 250 million users * 10 messages/user = 2.5 billion messag...
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