System Design Interview: End-to-End Architecture Deep Dive

Task

Explain the end-to-end architecture of a production system you built or can credibly design. Use a concrete example (e.g., real-time personalized feed, event ingestion pipeline, payments, notifications). Cover the full request and data lifecycle: clients, APIs, services, storage, async infrastructure, and observability.

For Each Module, Discuss

1. Purpose and responsibilities.
2. How to speed up the service (latency, throughput, resource efficiency).
3. Expected QPS/EPS with back-of-the-envelope estimates and assumptions.
4. Data model, partitioning/sharding, and cache strategy.
5. Failure modes, backpressure, and fallback behavior.
6. If Kafka (or a similar log) is involved:
   • Producer, broker, and consumer configuration.
   • Delivery guarantees (at-most-once, at-least-once, exactly-once) and how they are achieved.
   • Idempotency, retries, reprocessing, DLQs, and schema evolution.

Constraints to State

• Latency SLOs (e.g., p95 100 ms for reads; p99 for critical paths).
• Traffic assumptions (DAU/MAU, sessions/day, requests/session, peak factor).
• Data retention and compliance needs.

Deliverables

• High-level architecture diagram (describe in words if you can’t draw).
• Module-by-module walkthrough with the points above.
• Capacity planning math (QPS, partitions, cache sizes) and key configuration choices.