Interesting. I wonder if the empty directories are in a slightly different place. If I substitute a 'T' for the 'C', I noticed one of my systems has 15,000 empty dirs in that place (a lot, but still far less than the 300,000 in the 'C' directory, though.
ls /private/var/folders/*/*/T/com.apple.metadata.mdworker
/Volumes/.timemachine/29CB9C93-2A70-454E-BFED-E020E4BB03DC/2021-03-17-143536.backup which I believe is the system snapshot of the last time I updated the system.
That's interesting. It may be the source of the errors for you. I never see volumes like that mounted, but I know Time Machine works somewhat differently depending upon macOS version and the volume's filesystem format (I'm runnning Mojave). It seems to me that it wouldn't hurt for you to add that volume to your spotlight exclusions (System Preferences-->Spotlight-->Privacy).
I can't add any of those volumes to the exclusion list. There is always an error.
On my Mojave and High Sierra systems, nothing happened, as far as I can tell. I deleted all but the last seven days worth of the folders in the 'C' directory. New ones are still created, but not at a very rapid pace.
I've tried (using 'lsof') to figure out what files the mdworker processes are accessing at or near the time of these errors, but I have not been successful. I've finally given up, deciding that it's not a big problem.
I don't know what those snapshots are, either. I think Spotlight will, by default, index every volume mounted in '/Volumes'. You might be able to turn off indexing for that particular volume by using the 'mdutil' command as follows...
mdutil -s /Volumes/.timemachinemdutil -i off /Volumes/.timemachine$ mdutil -s /Volumes/.timemachine
/System/Volumes/Data/Volumes/.timemachine:
Error: unknown indexing state.$ mdutil -i off /Volumes/.timemachine
/System/Volumes/Data/Volumes/.timemachine:
Error: invalid operation.
Error: unknown indexing state.
$ sudo mdutil -Ea
/:
Indexing enabled.
/System/Volumes/Data:
Indexing enabled.
/Volumes/.timemachine/TC Living Room._afpovertcp._tcp.local/1FA797B5-4B77-4AE2-99C1-47BE3617BDB2/O+L Backup:
2021-04-11 22:48:21.068 mdutil[75923:1296247] mdutil disabling Spotlight: /Volumes/.timemachine/TC Living Room._afpovertcp._tcp.local/1FA797B5-4B77-4AE2-99C1-47BE3617BDB2/O+L Backup -> kMDConfigSearchLevelOff
Indexing and searching disabled./Volumes/.timemachine on that list.
Bash:$ mdutil -s /Volumes/.timemachine /System/Volumes/Data/Volumes/.timemachine: Error: unknown indexing state.
Bash:$ mdutil -i off /Volumes/.timemachine /System/Volumes/Data/Volumes/.timemachine: Error: invalid operation. Error: unknown indexing state.
Sorry but it isn't working —I tried before— and I even thing that those volumes are in principle excluded from Spotlight, but it isn't working.
If I filter out the mdwork messages, I can see there is a memory allocation error ( root cause?) .
I don't know if you are replying to me or to @Brian33. Anyhow…
Service exited due to SIGKILL | sent by mds[88] on the system log…
I get a lot of those "Class xxxxx is implemented in both yyyyyy and zzzzz" messages, too. I get them for many non-MDS classes, so I never felt they were related to the mdworker errors, though. As far as I can tell, they aren't a problem (except for spamming the system.log file).
To get rid of some orphaned directories I used the 'find' command with the '-empty' predicate to ensure I didn't delete any non-empty folders and '-mdtime' to delete those older than 7 days. Refine the command without the '-delete' predicate until you are sure it does what you want, then add '-delete' to the end of the command to do the for-real delete.
#!/bin/bash
# Use this command to delete all empty dirs older than 7 days
DAYS=7
CDIR=`ls -d /private/var/folders/*/*/C/com.apple.metadata.mdworker`
echo "Working on $CDIR..."
echo "...this may take awhile..."
COUNT=`find $CDIR -empty -mtime +${DAYS} -ls | wc -l`
echo "===> This user has $COUNT empty directories older than $DAYS days there."
CMD="find $CDIR -empty -mtime +$DAYS -delete"
echo "...about to run this command:"
echo " $CMD"
echo
echo "===> REALLY DELETE all empty directories older than $DAYS days there?"
echo "(Answer 1 or 2)"
select ANS in "Yes" "No"; do
case $ANS in
Yes ) $CMD; echo "Done."; break;;
No ) echo "OK, aborted."; exit;;
* ) echo "OK, aborted."; exit;;
esac
done
? [= Sender com.apple.xpc.launchd] claim only
* ignoresudo killall -HUP syslogd
? [= Sender com.apple.xpc.launchd] claim only
* ignoresudo killall -HUP syslogdman asl.conf
May 8 18:41:44 DreamOn com.apple.xpc.launchd[1] (com.apple.mdworker.shared.01000000-0600-0000-0000-000000000000[16268]): Service exited due to SIGKILL | sent by mds[1182]
May 8 18:41:44 DreamOn com.apple.xpc.launchd[1] (com.apple.mdworker.shared.20000000-0300-0000-0000-000000000000[16272]): Service exited due to SIGKILL | sent by mds[1182]
May 8 18:41:45 DreamOn com.apple.xpc.launchd[1] (com.apple.mdworker.shared.09000000-0100-0000-0000-000000000000[16211]): Service exited due to SIGKILL | sent by mds[1182]I also get zero matches so I assume Apple fixed it or changed it.
ls -l /private/var/folders/*/*/C/com.apple.mdworker.bundle | wc -l