This is a multi tenant environment. Today, we upgraded to 3.0.9-5.
After we upgraded, we wanted to make sure that maintenance will not delete anything, so we clicked on the maintenance module, it simply didn’t load. It had this green bar running on top indicating that it is trying to load, but it didn’t complete. In the meantime we were able to go to other modules, as well as clicking again on maintenance and we were able to see it.
Prior to doing that, the CPU was stable the entire time. After doing that, the CPU jumps every 60 seconds. It’s not spiking, but a nice jump.
It seems like it is something with MySQL, please see screenshot from htop: