Shopee Flash Sale Architecture: Rate Limiting & Redis
Answer-first: How Shopee engineers prevent crashes during 11.11 flash sales: rate limiting, Redis inventory locks, traffic shields, and microservices resilience. At exactly midnight on 11.11, Shopee users across Southeast Asia and Taiwan simultaneously tap the same button. In the first 10 seconds of a flash sale, a single product page can receive requests from millions of concurrent sessions — all competing to purchase the same 1,000 units of inventory. One oversell, one server crash, or one database deadlock during that window results in a cascade of chargebacks, angry users, and front-page news headlines. ...