On one of the servers, I have mysqld running as slave DB.
The CPU usage is 175% at the moment used by mysqld.
Here are the results of SHOW PROCESSLIST;
+----------+-------------+-----------+---------+---------+---------+-----------------------------------------------------------------------------+------------------------------------------------------------------------------------------------------+
| Id | User | Host | db | Command | Time | State | Info |
+----------+-------------+-----------+---------+---------+---------+-----------------------------------------------------------------------------+------------------------------------------------------------------------------------------------------+
| 109029 | system user | | NULL | Connect | 2346123 | Waiting for master to send event | NULL |
| 109030 | system user | | NULL | Connect | 0 | Slave has read all relay log; waiting for the slave I/O thread to update it | NULL |
| 12944426 | root | localhost | NULL | Query | 0 | NULL | SHOW PROCESSLIST |
| 12944443 | mdpipub | localhost | mdpipub | Sleep | 0 | | NULL |
| 12944445 | mdpipub | localhost | mdpipub | Sleep | 0 | | NULL |
| 12944463 | mdpipub | localhost | mdpipub | Sleep | 0 | | NULL |
| 12944466 | mdpipub | localhost | mdpipub | Sleep | 0 | | NULL |
| 12944467 | mdpipub | localhost | mdpipub | Sleep | 0 | | NULL |
| 12944469 | mdpipub | localhost | mdpipub | Sleep | 0 | | NULL |
| 12944470 | mdpipub | localhost | mdpipub | Sleep | 0 | | NULL |
| 12944471 | mdpipub | localhost | mdpipub | Sleep | 0 | | NULL |
| 12944476 | mdpipub | localhost | mdpipub | Sleep | 0 | | NULL |
| 12944479 | mdpipub | localhost | mdpipub | Sleep | 0 | | NULL |
| 12944482 | mdpipub | localhost | mdpipub | Sleep | 0 | | NULL |
| 12944484 | mdpipub | localhost | mdpipub | Sleep | 0 | | NULL |
| 12944485 | mdpipub | localhost | mdpipub | Sleep | 0 | | NULL |
| 12944488 | mdpipub | localhost | mdpipub | Sleep | 0 | | NULL |
| 12944490 | mdpipub | localhost | mdpipub | Sleep | 0 | | NULL |
| 12944491 | mdpipub | localhost | mdpipub | Sleep | 0 | | NULL |
| 12944492 | mdpipub | localhost | mdpipub | Sleep | 0 | | NULL |
| 12944493 | mdpipub | localhost | mdpipub | Sleep | 0 | | NULL |
| 12944495 | mdpipub | localhost | mdpipub | Sleep | 0 | | NULL |
| 12944496 | mdpipub | localhost | mdpipub | Sleep | 0 | | NULL |
| 12944498 | mdpipub | localhost | mdpipub | Sleep | 0 | | NULL |
| 12944499 | mdpipub | localhost | mdpipub | Sleep | 0 | | NULL |
| 12944501 | mdpipub | localhost | mdpipub | Sleep | 0 | | NULL |
| 12944502 | mdpipub | localhost | mdpipub | Query | 0 | Sending data | SELECT DISTINCT(article_id) FROM authors WHERE CONCAT(
firstname,
|
| 12944503 | mdpipub | localhost | mdpipub | Sleep | 0 | | NULL |
| 12944504 | mdpipub | localhost | mdpipub | Query | 0 | Sending data | SELECT DISTINCT(article_id) FROM authors WHERE CONCAT(
firstname,
|
+----------+-------------+-----------+---------+---------+---------+-----------------------------------------------------------------------------+------------------------------------------------------------------------------------------------------+
This is because 2 potential heavy SELECT queries are running. The load of all threads is then summed up for the main process and may show more than 100%.
I fund the problem. I got an attack on the server by someone executing constantly the search function on the website. I just banned this IP and it is fine at the moment.