Shopee Flash Sale Engine: Redis Lua & Overselling
Answer-first: Shopee prevents overselling during high-concurrency flash sales by combining local memory caching, Redis inventory sharding, and atomic Lua script decrements. This multi-tier architecture isolates hot keys in Redis memory shards and evaluates stock availability in sub-milliseconds without acquiring relational database locks. Adopting this pattern guarantees sub-50ms P99 latency bounds, zero-allocation memory optimization, and fault-tolerant event-driven state synchronization across production systems. Chapter 2: Flash Sale Engine - The Mystery Behind Redis and Hot Keys ← Series hub | ← Prev | Next → ...