Design Image Processing Infrastructure for mobile apps

Last updated: February 13, 2026

Quick Overview

Design a event-driven image processing system that handles millions of requests. Discuss trade-offs in consistency, availability, and performance.

Zscaler
System Design
Software Engineer
Zscaler
February 13, 2026
Software Engineer
System Design Round
System Design
Hard

44

5

813 solved


Design a event-driven image processing system that handles millions of requests. Discuss trade-offs in consistency, availability, and performance.

ML system design at Zscaler goes beyond model selection. This System Design Round question evaluates your ability to design end-to-end ML pipelines, from data collection to model serving, while considering production constraints like latency and reliability.

What the Interviewer Expects
  • Design the full ML lifecycle from data collection to model monitoring
  • Address cold start, exploration/exploitation, and model freshness
  • Discuss multi-objective optimization and ranking systems
  • Plan for model debugging, fairness, and bias mitigation
  • Design the feature store and training pipeline for scale
  • Address model versioning, canary deployments, and rollback strategies
  • Discuss the data flywheel and long-term system evolution
Key Topics to Cover
Data collection and labeling strategy
Training pipeline and infrastructure
Model serving and latency optimization
A/B testing and experimentation
Feature engineering and feature stores
Online vs offline evaluation
How to Approach This
  1. Start by clarifying functional and non-functional requirements with the interviewer.
  2. Estimate the scale: QPS, storage, bandwidth. This drives your design decisions.
  3. Draw a high-level architecture first, then deep dive into 1-2 critical components.
  4. Discuss trade-offs explicitly (e.g., consistency vs availability, SQL vs NoSQL).
  5. Address failure scenarios, monitoring, and how the system handles 10x traffic spikes.
Possible Follow-up Questions
  • How would you debug a model that works well offline but poorly online?
  • How would you handle a 10x increase in prediction requests?
  • How would you handle the cold start problem?
  • What is your model retraining strategy?
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Sample Answer
Requirements Clarification

Before diving into the architecture, clarify the scope with the interviewer. For Image Processing Infrastructure for mobile apps, key functional requi...

Capacity Estimation

Estimate the scale to drive design decisions. Assume 100M DAU with an average of 10 actions per user per day = 1B requests/day ~ 12K QPS average, ~36K...


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