We are using moodle 3.9.1 with mariadb server on seperate centos 8 servers. it has been running for 6+ months with out any issue. Recently in 1 modlue when the teacher tried to view the submiited assginments it throws 504 bad gateway error.
When checked the issue for that perticular assinment maria db server cpu goes 100% .I checked apache and it was working fine. maria db is on default configuration. no errors in mariadb logs.
any clue reagarding where to begin with helps me a lot