连接池

Sync.pool 会被gc， 所以不能放连接池

Reference

• Go-Redis 连接池（Pool）源码分析 https://pandaychen.github.io/2020/02/22/A-REDIS-POOL-ANALYSIS/
• go-redis 连接池实现思想: https://jishuin.proginn.com/p/763bfbd2cb12
• 作为 Gopher 你一定要懂的连接池 https://mp.weixin.qq.com/s?__biz=MzAxMTA4Njc0OQ==&mid=2651441341&idx=3&sn=4e7fbf93692593620a411875bd07b7ca&chksm=80bb164fb7cc9f5968c7c5d6e97da9e1bfba84db938378ddce3331d4dd1d7b222d8d695b968d&scene=21#wechat_redirect
• Go 连接池相关总结：HTTP、RPC、Redis 和数据库等 https://mp.weixin.qq.com/s?__biz=MzAxMTA4Njc0OQ==&mid=2651440800&idx=2&sn=9950309a86cb94e5a6fa6e28ddc0f8a8&chksm=80bb1852b7cc91443a5f40b5fe8f5910474276399e7eea311cd7eb02950f21c9ec5a5ca1aa15&scene=21#wechat_redirect
• Go：数据库连接池 https://mp.weixin.qq.com/s?__biz=MzAxMTA4Njc0OQ==&mid=2651440264&idx=3&sn=bbf2c89da3034e4cc2eca5faf755001c&chksm=80bb1a7ab7cc936c2e1d092918c1d8e0831f101d34da7bafaff21516024648352ceaa7063e2c&scene=21#wechat_redirect
• 鹅厂 Go 内存池/对象池技术实战爬坑指南： https://mp.weixin.qq.com/s?__biz=MzAxMTA4Njc0OQ==&mid=2651439937&idx=1&sn=35b0f6446c77dbe9c6eb799213438c13&chksm=80bb1db3b7cc94a52f1c959c4cdaafe283153ea11153c2381e03b6bcd28774ce470bd97fa346&scene=21#wechat_redirect