← J.P. Morgan Interview Insights
This took me a minute to orient because they explicitly said don't rewrite it, just improve it.
Start by clarifying the current architecture and requirements, then propose a redesign that separates read and write paths, introduces caching and asynchronous processing, and uses event-driven notifications for out-of-stock alerts. Focus on trade-offs between consistency, latency, and complexity, and explain how each change addresses the specific goals.
Pro tip: Emphasize idempotency and graceful degradation—ensure that under high load or partial failures, the cart remains consistent and users still get timely notifications. Also, mention monitoring and metrics to validate improvements.
Ask questions to understand the expected scale, latency targets, consistency needs, and current pain points. Identify which operations are most frequent and where latency likely originates.
Suggest separating read and write models (CQRS), adding a cache (e.g., Redis) for cart reads, and using a message queue for asynchronous inventory checks and notifications.
Explain how writes update the database and invalidate/update the cache, and how inventory changes trigger events. Discuss consistency models (e.g., eventual consistency for notifications) and how to handle conflicts.
Describe using WebSockets or Server-Sent Events (SSE) to push out-of-stock alerts to users, with a fallback to polling or email if needed. Ensure notifications are reliable and not duplicated.
Cover trade-offs like increased complexity, potential stale reads, and cost. Mention monitoring, alerting, and gradual rollout to mitigate risks.
AI-generated suggestions, not part of the candidate's original notes. May be inaccurate — verify before relying on them.