There has been a history of people reporting mdworker processes taking up lots of CPU time on older machines, but apart from vague suggestions to just re-create the entire Spotlight index, I could not find any diagnosis information.
My (modern) machine has no performance issues, I would just like to understand the reason for the "Service exited due to SIGKILL" messages that flood my system logs:
com.apple.xpc.launchd (com.apple.mdworker.shared.00000000-0300-0000-0000-000000000000): Service exited due to SIGKILL | sent by mds
Are there any logs I could use to find out what is actually going wrong; i.e. whether the indexing processes are stuck at a certain file? Is there a way to increase the messages' verbosity?
A bit of system information: This is happening on an iMac running Catalina (10.15.6), with just a few hundred GB of files. For testing purposes, I limited Spotlight categories (through System settings) to apps and contacts only, but that did not seem to make any difference. The machine has no directories where files might change constantly, no directories with excessive numbers of files and, as far as I know, no totally unusual file formats on it.