What is the 'deleted' daemon in macOS?

deleted is the process for CacheDelete, which is used to purge caches on disk. Looking in /System/Library/CacheDelete/ you can see what services are registered as a client.

I came here due to an issue on my MacBook Pro (2018 15") running on macOS Catalina 10.15.7.

In fact, the deleted process was showing up in my process list and consuming around 50% CPU - more or less. After following some hints which I found here and there (deinstalling iStats, resetting SMC and so on) I realized that this process kept on being open as long as my About this Mac window was open. The deleted process disappears shortly after closing the About this Mac window.

For me, this problem was being caused by problems with iStat Menus on macOS Sierra 10.12.0. There seems to be a bug which causes issues with the deleted process. Once I uninstalled iStat Menus the problem ceased.

This issue has been resolved, see https://bjango.com/help/istatmenus5/knownissues/

I found that the deleted was activated when I started the Disk Utiulity and selected disk container which has macOS system.

In Console.app search for deleted and look for an entry like this:

default 17:23:45.621668+0100    deleted 1426 com.apple.deleted_helper APFS Purgeable update for Calling process: iStat Menus Status on "/Volumes/ExternalSSD2TB - Data" ET: 1.452986,  results:
default 17:23:45.621690+0100    deleted     CACHE_DELETE_TOTAL_AVAILABLE : 0
default 17:23:45.621879+0100    deleted     CACHE_DELETE_ID : com.apple.cache_delete
default 17:23:45.622014+0100    deleted     CACHE_DELETE_URGENCY : 0
default 17:23:45.622149+0100    deleted     CACHE_DELETE_TOTAL_FSPURGEABLE : 0
default 17:23:45.622311+0100    deleted     CACHE_DELETE_CALLING_PROCESS : iStat Menus Status
default 17:23:45.622447+0100    deleted     CACHE_DELETE_QUERY_PATH : SLOW
default 17:23:45.622582+0100    deleted     CACHE_DELETE_NO_CACHE : 1
default 17:23:45.622718+0100    deleted     CACHE_DELETE_VOLUME : /Volumes/MBP
default 17:23:45.622838+0100    deleted     CACHE_DELETE_TOTAL_PURGEABLE : 1
default 17:23:45.622984+0100    deleted     CACHE_DELETE_ELAPSED_TIME : 0.145932097

The line CACHE_DELETE_CALLING_PROCESS : iStat Menus Status reveals that the iStat Menus Status process is causing the calls.

This issue started occurring for me when I activated the Disks option in iStat.

After removing unchecking this option, the issue still occurred, but after I killed the iStat Menus Status process from Activity Manager (I also killed some other ones too), the deleted activity went away entirely.

Looks like an iStat bug.