详解如何发现并解决Redis热点Key问题

redis-cli MONITOR

config set slowlog-log-slower-than 1000  # 设置记录超过 1000 微秒（1 毫秒）的操作
config set slowlog-max-len 1024        # 设置 SLOWLOG 最大长度
slowlog get                            # 获取 slowlog 记录

#!/bin/bash

END=$(redis-cli dbsize); 
for i in $(seq 0 $END); 
do 
  KEY=$(redis-cli randomkey); 
  redis-cli object freq $KEY; 
done

pip install rdbtools
rdb --command memory ./dump.rdb --bytes > memory.csv

# 安装 redis-hotkey 插件
git clone https://github.com/carlos1f/redis-hotkey.git
cd redis-hotkey
make && make install

server1:
    ip: 127.0.0.1
    port: 6379
    weight: 1
server2:
    ip: 127.0.0.1
    port: 6380
    weight: 1

config set maxmemory-policy allkeys-lru

# 请求合并逻辑
import redis
import time

cache = redis.StrictRedis()

def get_data(key):
    if cache.exists(key):
        return cache.get(key)
    # 请求合并操作
    lock_key = f"{key}_lock"
    if cache.setnx(lock_key, 1):
        cache.expire(lock_key, 5)
        # 从数据库读取数据
        data = fetch_data_from_db(key)
        cache.set(key, data, ex=60)  # 缓存有效时间 60s
        cache.delete(lock_key)
        return data
    else:
        time.sleep(0.1)  # 等待其他请求获取数据
        return cache.get(key)

http {
    limit_req_zone $binary_remote_addr zone=req_one:10m rate=1r/s;
    server {
        ...
        location / {
            limit_req zone=req_one burst=5 nodelay;
        }
        ...
    }
}

# 多级缓存示例
import time

local_cache = {}
cache = redis.StrictRedis()

def get_data(key):
    if key in local_cache:
        return local_cache[key]
    if cache.exists(key):
        data = cache.get(key)
        local_cache[key] = data
        return data
    # 从数据库读取数据
    data = fetch_data_from_db(key)
    cache.set(key, data, ex=60)  # 缓存有效时间 60s
    local_cache[key] = data
    return data

# 定期数据清理
import redis

cache = redis.StrictRedis()

def clean_expired_keys():
    cursor = '0'
    while cursor != 0:
        cursor, keys = cache.scan(cursor)
        for key in keys:
            if cache.ttl(key) == -1:
                cache.delete(key)