← Walmart Labs Interview Insights
This is the kind of question where you can go a dozen different directions and I wasn't sure which layer they wanted me to focus on.
Start by clarifying requirements such as expected traffic volume, latency tolerance, and carrier API rate limits. Then propose a multi-layered optimization strategy covering caching, batching, asynchronous processing, and resilience patterns like circuit breakers and retries with backoff. Conclude by discussing trade-offs between consistency, cost, and complexity.
Pro tip: Emphasize idempotency and deduplication of requests to avoid duplicate carrier calls, and mention that you would monitor carrier-specific error rates to dynamically adjust retry policies. This shows you think about real-world operational concerns beyond just performance.
Ask about expected request volume, latency SLAs, carrier API rate limits, and data freshness requirements. This ensures your optimizations target the right bottlenecks.
Cache delivery statuses with appropriate TTLs and deduplicate concurrent requests for the same package to reduce redundant carrier calls.
Decouple status checks from user requests via message queues, and batch multiple package queries into single carrier API calls where supported.
Apply circuit breakers, retries with exponential backoff, and fallback responses to handle carrier outages gracefully without cascading failures.
Track metrics like cache hit ratio, carrier latency, and error rates; use these to tune TTLs, retry policies, and scaling strategies.
AI-generated suggestions, not part of the candidate's original notes. May be inaccurate — verify before relying on them.