launchd

launchd itself rarely does heavy work. When it appears busy, it is often starting processes over and over, for example a background item that crashes and gets relaunched repeatedly.

Look in Activity Monitor for a process that keeps appearing and disappearing, or check System Settings, General, Login Items to see which background items are allowed to run. Turning off a background item you do not need is a safe first step.

The system launchd is the parent of the whole system. It cannot be quit in a normal way, and stopping a user launchd would end your session. Fix the process it keeps starting instead.

When launchd looks busy, the real question is what it keeps starting. Check the background items you have allowed first.

1. Choose Apple menu > System Settings, click General in the sidebar, then click Login Items & Extensions.
2. Look through the items that open at login and the list of apps allowed to run in the background. Anything you do not recognize or no longer use is a candidate.
3. Turn off one item at a time and watch launchd in Activity Monitor. If its CPU drops, you have found the item.
4. If the item belongs to an app you still use, update the app or check its own settings. If you no longer use the app, uninstall it with its own uninstaller if it has one.

A service that crashes and gets relaunched shows up as a process that appears in Activity Monitor for a moment, disappears, and comes back with a new PID. Sorting the CPU tab by PID, highest first, makes these easier to catch, since each relaunch gets a higher number.

In Terminal, launchctl list shows the jobs launchd has loaded for your account in three columns: the PID if the job is running, its last exit status, and its label. A dash in the first column means the job is not running right now. A negative status is the signal that stopped the job, and many Apple jobs show one because macOS stops idle services on purpose, so a nonzero status alone is not a problem.

For a label you suspect, run launchctl print gui/$(id -u)/<label>. Its output includes a runs line, the number of times launchd has started the job. If that number keeps rising every time you check, the job is in a restart loop. These commands only read information.

launchd reads job definitions from a few folders. Apple's own jobs are in /System/Library/LaunchAgents and /System/Library/LaunchDaemons, and you should leave those alone. Items installed by other apps are usually in these folders:

• ~/Library/LaunchAgents: agents for your user account only.
• /Library/LaunchAgents: agents for every user, installed by an administrator or an app installer.
• /Library/LaunchDaemons: system wide daemons installed by an administrator or an app installer.

launchd runs a few kinds of jobs, and the names show up in Activity Monitor and in launchctl output. A daemon is a system wide service with one copy for everyone on the Mac, and it does not show any interface. An agent runs separately for each user who is logged in, and it can interact with that user.

launchd also manages XPC services, small helper programs bundled inside apps and frameworks. When an app hands work to one of these, launchd starts it on demand and it appears in Activity Monitor as its own process. That is one reason processes with unfamiliar names come and go while you use an app.