MySQL has a large number of unauthenticated users

Execute the Show Processlist statement in MySQL and you can see that a large number of unauthenticated user processes are stuck. I heard this is a MySQL bug. The following article will introduce the solution to a large number of unauthenticated users in MySQL, if you have encountered such problems, refer.

Problem status

Restarting mysql also fails. You can only see information similar to the following:

Forcing close of thread 12232 user: 'root'

Use mysqladmin to easily monitor mysql:

Mysqladmin-uroot-p ******** status-I 1

It is found that Queries per second avg is only about 200, which can be said to be very low, but Threads is indeed very unstable, and it will actually upgrade more than 200 instantly. In general, this thread value will not be higher than 5 single digits!

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 Query IP-> DNS, because reverse query and resolution are too slow to cope with fast and massive queries.

Solution

Solution: add the -- skip-name-resolve option when starting MySQL.

Reload the configuration file or restart the MySQL service.