1.查看最大连接数：
show variables like ‘%max_connections%‘;
2.查看当前实时连接数：
show status like ‘Threads%‘;
3.查看所有连接IP地址的连接数：
select SUBSTRING_INDEX(host,‘:‘,1) as ip , count(*) from information_schema.processlist group by ip;
原文：https://www.cnblogs.com/jiahm/p/13040022.html