1.错误情况
Host is blocked because of many connection errors; unblock with 'mysqladmin flush-hosts'
2.原因
从异常信息可以得知就是出现了太多的链接错误。可能原因有，错误的请求、连接超时过多等等。
3.解决
3.1如何解决
https://dev.mysql.com/doc/refman/8.0/en/host-cache.html#host-cache-flushing
Change the value of the
host_cache_sizesystem variable. This requires theSYSTEM_VARIABLES_ADMINprivilege (or the deprecatedSUPERprivilege).Execute a
TRUNCATE TABLEstatement that truncates the Performance Schemahost_cachetable. This requires theDROPprivilege for the table.Execute a
FLUSH HOSTSstatement. This requires theRELOADprivilege.Execute a mysqladmin flush-hosts command. This requires the
DROPprivilege for the Performance Schemahost_cachetable or theRELOADprivilege.
3.2 host_cache 内部有什么
https://dev.mysql.com/doc/refman/8.0/en/performance-schema-host-cache-table.html
4.可问题还没解决
通过flush hosts 清除了被锁的信息，可以正常地访问数据库了。但是同一台机器上的其他服务却可以进行访问数据，难道锁的不是整个ip吗？
mysql中的host
从https://dev.mysql.com/doc/refman/8.0/en/performance-schema-hosts-table.html可以看到host 是
- The host from which the client connected. This is NULL for an internal thread, or for a user session that failed to authenticate.
通过指令能够更加清楚明白。
mysqladmin proc stat
host是指程序运行的ip+端口
