is blocked beacuse of many connection errors; unblock with 'mysqladmin flush-hosts'

mysql会有too many connections的问题，有时候明明connection允许连接很多了，但还是会有

is blocked beacuse of many connection errors; unblock with 'mysqladmin flush-hosts'这样的错误。很多时候不是连接数量限制的问题，而是需要把连接计数清零。

在mysql中运行:

flush hosts;

然后就可以了。