MySQL appears with a large number of unauthenticated user

Problem status

Restart MySQL is also a failure, look at the errorlog of MySQL, you can only see the following information similar to:

Forcing close of thread 12232 User: ' Root '

With mysqladmin simple monitoring of the next MySQL situation:

mysqladmin-uroot-p******** Status-i 1

found that queries per second AVG Only about 200, can be said to be very low, but threads is very unstable, incredibly will upgrade more than 200, in general, this thread of this value is not higher than 5 of the Single-digit!

mysqladmin-uroot-p******** processlist

| 2007 | Unauthenticated user | 192.168.4.29:58519 | | Connect | | Login | |

| 2008 | Unauthenticated user | 192.168.4.29:58553 | | Connect | | Login | |

| 2009 | Unauthenticated user | 192.168.4.29:58571 | | Connect | | Login | |

| 2010 | Unauthenticated user | 192.168.4.29:58577 | | Connect | | Login | |

| 2011 | Unauthenticated user | 192.168.4.29:58579 | | Connect | | Login | |

| 2012 | Unauthenticated user | 192.168.4.29:58589 | | Connect | | Login | |

Cause analysis

MySQL will try to reverse the ip->dns, because the reverse lookup resolution is too slow, unable to cope with the rapid and multiple queries.

Solutions

The solution is simple: When you start MySQL, add the--skip-name-resolve option

Reload the configuration file or restart the MySQL service.