最大连接数
show variables like 'max_connections';
超时时间
show global variables like '%timeout%';
超时分析：
TimeoutError: QueuePool limit of size 10 overflow 10 reached, connection timed out, timeout 30
https://reality0ne.com/sqlalchemy-zhong-de-queuepool-chu-xian-timeouterror/
标签：10,like,show,variables,参数,MySQL,超时 From： https://www.cnblogs.com/Primzahl/p/17579963.html