Since 2005, macOS has had the master launcher launchd and its LaunchAgents and LaunchDaemons. Then in 2014 Apple added Duet Activity Scheduler to run tasks when conditions are suitable.
DAS
How do the SMC and CoreDuet manage the systems in your Mac, and should you fiddle with them?
Automatic Time Machine backups aren’t scheduled to run at precise times, but when it’s convenient. This explains how, and what to do if goes wrong.
Why XProtect Remediator scans can report BadPluginServiceSignature status_code 31 and abort, and why you don’t need to do anything about it.
What can you do when your Time Machine backups stop running regularly? Or another background activity has gone missing?
You’ve just installed an update to macOS security software, then it gives you a status of ‘Unknown’ caused by [] and stops working. What’s wrong?
While macOS uses DAS-CTS to schedule hundreds of background activities, third-parties normally use launchd. Comes with a full diagram explaining DAS-CTS.
How running a background task takes a tiny fraction of second, although the task itself takes seconds or minutes, and why it’s run on E cores.
How macOS schedules tasks like making automatic Time Machine backups, from property list to transactions between DAS and CTS.
The story of how Mac OS X went from cron, to launchd, and ended up with Duet Activity Scheduler, to schedule background activities like backups.
The Eclectic Light Company 