亿级高并发秒杀系统架构：动静分离、Redis Lua 原子扣减与消息削峰实战

#01 1. What a Flash Sale Really Is, and Its Four Fatal Flaws

The defining challenge of a flash sale is extreme, instantaneous read/write skew. In the few seconds after the sale opens, millions of users fire order requests concurrently, all hammering a single database row.

Send that straight at MySQL and, connection pool or not, database CPU pegs at 100% within 50ms, connections are exhausted, and every service on the site cascades into failure.

#02 2. A Seven-Layer Traffic Funnel

We filter and reject in layers:

Client layer: a greyed-out button with a countdown, debounce control, and staggered CAPTCHA;
CDN edge nodes: fully cached static pages, blocking 90% of page traffic from ever reaching origin;
API gateway (Kong / Envoy): IP/token allowlists and denylists plus sliding-window rate limiting;
Distributed cache (Redis Cluster): atomic Lua deduction, letting only valid requests through;
Async message queue (RocketMQ): writes to MySQL asynchronously at a steady rate.

-- Redis Lua 脚本：原子预扣减库存与防重复下单 local stockKey = KEYS[1] local userOrderKey = KEYS[2] local userId = ARGV[1] local quantity = tonumber(ARGV[2]) -- 1. 检查用户是否已下单 if redis.call('SISMEMBER', userOrderKey, userId) == 1 then return -1 -- 已经下过单，防止重复 end -- 2. 检查剩余库存 local currentStock = tonumber(redis.call('GET', stockKey) or '0') if currentStock < quantity then return 0 -- 库存不足 end -- 3. 原子扣减并记录用户 redis.call('DECRBY', stockKey, quantity) redis.call('SADD', userOrderKey, userId) return 1 -- 扣减成功

亿级高并发秒杀系统架构：动静分离、Redis Lua 原子扣减与消息削峰实战

CDN 边缘层

网关限流器

Redis Lua 集群

RocketMQ 集群

#01 1. What a Flash Sale Really Is, and Its Four Fatal Flaws

#02 2. A Seven-Layer Traffic Funnel