现象是访问Nginx上的域名，延迟高，抓包看到TCP Retransmission比较多
转自：
https://blog.51cto.com/xiao987334176/1663462
详细参考：
https://www.cnblogs.com/lulu/p/4149312.html
https://www.cnxct.com/coping-with-the-tcp-time_wait-state-on-busy-linux-servers-in-chinese-and-dont-enable-tcp_tw_recycle/