Issue Process with user syslog and command cache-main is constantly at 100% CPU

[Crim]

I have a Plesk server on Ubuntu 18 and every day this process uses 100% until I kill it. Does anybody know what this process does?
It runs with user syslog and command cache-main.

 

[Monty]

That process looks suspicious to me. You should investigate it to find out where the binary lives and which process was calling it.

List open files/descriptors/sockets of the process: lsof -p 9977
Retrieve parent process ID: ps -o ppid= -p 9977
Then do lsof -p with the parent process ID
Also, do a full "ps auxwww" to list all of your processes.

 

[Crim]

Looks like it has something to do with Varnish. I have Varnish running in a Docker container. Is it possible this is visible like this on the host?

 

[Monty]

Ah OK, so "cache-main" belongs to Varnish, so nothing suspicious.
I can't tell you why that varnish process has such a high CPU usage, you will have to debug that using varnishtop and other tools, but this is outside of the scope of Plesk. Also, check your varnish logs if you see anything that will give you an indication about what's going on.

 

[Crim]

Thanks for pointing me in the right direction!