MySQL DNS anti-resolution Problems

Recently, I found that the connection to the database in the new column is very slow. I log on to the MySQL database.

Mysql> show processlist;

| 20681949 | unauthenticated user | 10.10.4.193: 52497 | null | connect | reading from net | null |
| 20681948 | unauthenticated user | 10.10.4.193: 52495 | null | connect | reading from net | null

It is found that many unauthenticated users try to log on to MySQL. When this happens, the system will be very slow.

I checked the official MySQL website and learned that this is a special setting on an official system. I thought of it as a MySQL bug. No matter whether the link is through the hosts or IP mode, he will reverse query the DNS. mysqld will try to reverse query the IP address-> DNS, because reverse query resolution is too slow, you cannot cope with excessive queries.

Solution:

/Usr/local/MySQL/bin/mysqld_safe -- skip-name-resolve -- user = MySQL &

Add the -- skip-name-resolve parameter to disable the DNS lookup function of MySQL.