Design a A/B Testing for Bloomberg
Last updated: September 12, 2025
Quick Overview
Design a high-throughput a/b testing system that handles millions of requests. Discuss trade-offs in consistency, availability, and performance.
Bloomberg
September 12, 20255
12
4,646 solved
Design a high-throughput a/b testing system that handles millions of requests. Discuss trade-offs in consistency, availability, and performance.
Bloomberg asks this during the Onsite 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 handle schema migrations with zero downtime?
- What happens if one of your database nodes goes down?
- How do you ensure data consistency across multiple services?
- What would the deployment pipeline look like for this system?
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Requirements
Functional Requirements:
- Experiment Creation: Users can create A/B tests specifying the variants to be tested, target audience, and duration.
- Traffic Allocation: The system must inte...
Capacity Estimation
To estimate capacity:
- Assume Bloomberg has 10 million active users.
- If we assume an A/B test can be run on 10% of users simultaneously, that’s 1 million users.
- If each user generates 5 requests ...
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