Redis最佳实践 - 秒杀

目录

• 入门

• 秒杀

• 队列

• 服务

• 测试

入门

启动Redis服务: docker run --name redis-in-action -p 6379:6379 -d redis

redis-cli

EVAL "return {KEYS[1], KEYS[2], ARGV[1], ARGV[2]}" 2 1 2 3 4

1) "1"
2) "2"
3) "3"
4) "4"

echo "return { KEYS[1], KEYS[2], ARGV[1], ARGV[2] }" >> hello.lua

redis-cli --eval hello.lua 1 2 , 3 4

1) "1"
2) "2"
3) "3"
4) "4"

关于Lua更多介绍 参考Lua简明教程

秒杀

• 高并发 - Redis内存

• 原子性 - Redis单线程

vim seckilling.lua

local n = tonumber(ARGV[1])
if not n or n == 0 then
    return 0
end
local vals = redis.call("HMGET", KEYS[1], "Total", "Booked")
local total = tonumber(vals[1])
local blocked = tonumber(vals[2])
if not total or not blocked then
    return 0
end
if blocked + n <= total then
    redis.call("HINCRBY", KEYS[1], "Booked", n)
    return n;
end
return 0

redis-cli script load "$(cat seckilling.lua)" # 58652c43df5e7752b7bb1f8e65e382299b5bd8b6

redis-cli

HMSET goodsId Total 100 Booked 0

HMGET goodsId Total Booked

1) "100"
2) "1"

SCRIPT EXISTS 58652c43df5e7752b7bb1f8e65e382299b5bd8b6

EVALSHA 58652c43df5e7752b7bb1f8e65e382299b5bd8b6 1 goodsId 1 

HMGET goodsId Total Booked

1) "100"
2) "1"

关于Redis单线程模型的更多讨论 可以参考为什么redis 是单线程的? & Redis单线程优势 & Redis is single threaded. How can I exploit multiple CPU / cores?

队列

• 发布-订阅 - Redis队列

• 缓存 - 高速Redis + MySQL

vim seckilling.lua

local n = tonumber(ARGV[1])
if not n or n == 0 then
    return 0
end
local vals = redis.call("HMGET", KEYS[1], "Total", "Booked")
local total = tonumber(vals[1])
local blocked = tonumber(vals[2])
if not total or not blocked then
    return 0
end
if blocked + n <= total then
    redis.call("HINCRBY", KEYS[1], "Booked", n)
    redis.call("LPUSH", KEYS[2], "Booked "..n)
    return n;
end
return 0

redis-cli script load "$(cat seckilling.lua)" # b191ffa49361dac8f9142f0eac552cecd0df2489

redis-cli

SCRIPT EXISTS b191ffa49361dac8f9142f0eac552cecd0df2489

EVALSHA b191ffa49361dac8f9142f0eac552cecd0df2489 2 goodsId orderList 1 

HMGET goodsId Total Booked

1) "100"
2) "2"

BRPOP orderList 60

1) "orderList"
2) "Booked 1"

这里只是将orderList的数据取出 实际项目中可以结合关系数据库处理该订单

服务

egg-init --type=simple server

cd server && cnpm i

cnpm i --save egg-redis

vim config/plugin.js

'use strict';

exports.redis = {
    enable: true,
    package: 'egg-redis',
};

vim config/config.default.js

'use strict';

module.exports = appInfo => {
    const config = exports = {};

    // use for cookie sign key, should change to your own and keep security
    config.keys = appInfo.name + '_1537341461009_7706';

    // add your config here
    config.middleware = [];

    config.redis = {
        client: {
            host: '127.0.0.1',
            port: 6379,
            password: '',
            db: '0',
        }
    };

    return config;
};

vim app/controller/home.js

'use strict';

const Controller = require('egg').Controller;

class HomeController extends Controller {
    async index() {
        const { ctx, app } = this;
        const code =
            `
local n = tonumber(ARGV[1])
if not n or n == 0 then
    return 0
end
local vals = redis.call("HMGET", KEYS[1], "Total", "Booked")
local total = tonumber(vals[1])
local blocked = tonumber(vals[2])
if not total or not blocked then
    return 0
end
if blocked + n <= total then
    redis.call("HINCRBY", KEYS[1], "Booked", n)
    redis.call("LPUSH", KEYS[2], "Booked "..n)
    return n;
end
return 0
        `;
        app.redis.defineCommand('seckilling', {
            lua: code
        });
        ctx.body = await app.redis.seckilling(2, 'goodsId', 'orderList', '1');
    }
}

module.exports = HomeController;

关于egg-redis的更多介绍 可以参考egg-redis & ioredis

cnpm run dev # localhost:7001

测试

redis-cli

HMSET goodsId Total 100 Booked 0

DEL orderList

sudo apt update

sudo apt install -y apache2-utils

ulimit -n 10000

ab -n 50000 -c 5000 http://192.168.56.1:7001/

关于ab的更多介绍 可以参考超实用压力测试工具－ab工具

redis-cli

HMGET goodsId Total Booked

1) "100"
2) "100"

参考

• 云数据库 Redis 版 - 最佳实践

• 利用redis + lua解决抢红包高并发的问题

• 秒杀抢购思路以及高并发下数据安全

• 在redis中使用lua脚本让你的灵活性提高5个逼格

• 使用 wrk 来测试 HTTP 性能