While doing maintenance to the Ubuntu server running mysql and apache2 using these commands:

SELECT tableschema AS “Database”, sum(datalength + indexlength)/1024/1024 AS “size in MB” FROM informationschema.TABLES GROUP BY table_schema;

optimize table wpcommentmeta, wpcomments, wplinks, wpodblogs, wpoptions, wppostmeta, wpposts, wptermrelationships, wptermtaxonomy, wptermmeta, wpterms, wpusermeta, wpusers, wpyoastseolinks, wpyoastseometa;

Then I went to the “Feedback” section of WordPress to delete old feedback around 24. Select them all and clicked “send” to trash.
Usually this process is quick. But it was taking a long time.
So I restarted the server, and now, mysql is taking all the cpu usage.

using the htop I see a bunch of /usr/sbin/mysql and one in particular is using most of CPU power.

Anyway to troubleshoot and fix this problem?