What is photoanalysisd on a Mac?

photoanalysisd is the background program that studies your Photos library. It finds faces so Photos can group people, works out scenes and objects, and builds the material for Memories. It runs mostly while the Mac is idle, it is busy after large imports, and the right move is to let it finish. It is part of macOS and is not harmful.

The name reads as photo, analysis, daemon. A daemon is just a background program with no window of its own.

What photoanalysisd does

A photo library starts as a pile of files. Photos turns it into something you can browse by person, by place and by topic, and that takes analysis.

Foreman’s one-line description is accurate: it finds faces, scenes and memories in your photo library, and runs mostly while the Mac is idle. In practice that covers:

• People. Faces are found and grouped so you can name them once and see all their pictures.
• Scenes and objects. Pictures are sorted so that searching for a kind of thing can find them.
• Memories and featured photos. Photos picks moments worth showing, which needs a look at what is in each picture.

All of this is done on the Mac. Nothing has to be sent anywhere for the analysis to happen.

It has a close cousin, mediaanalysisd, which analyses photos and videos for search, Live Text and Visual Look Up. The two often run at the same time after an import. What is mediaanalysisd on a Mac, and can you stop it? covers that one.

Why it runs when you are not using the Mac

macOS likes to do slow jobs when you are not asking for the processor. That is the reason this program is often busy overnight, or while a laptop sits on a desk, rather than while you work. If you open the lid in the morning and the fans are going, this is one of the usual suspects.

It also explains why it can look idle for weeks, then work for hours: it works when there is something new, and when the Mac has time.

What makes it busy

• A big import. Bringing in a camera card, or a folder of old photos, gives it thousands of new pictures to look at.
• iCloud Photos on a new Mac. Turning on iCloud Photos downloads your library, and every picture has to be analysed on this Mac.
• A restore or migration. Moving to a new Mac brings the library across, and the analysis is often done again.
• A macOS update. After an update, the recognition may be improved, and the library can be looked at again. See Why is my Mac slow after a macOS update?.

For a large library, the first complete pass can take a long while, and macOS spreads it over idle time. A library of many thousands of photos can take hours or days, depending on the Mac.

What to do

Let it finish. This is the main advice, and it is honest. Photos is only useful for people and search once the analysis is done, and stopping it just leaves the library half analysed.

Leave the Mac on. Analysis happens while the Mac is awake. A laptop that is closed and asleep does no analysis. If you want it done, leave a laptop open on power for a few hours, or a desktop on, and give it time.

Do not import everything at the worst time. Bring in big batches before a break rather than before an important call. Mac slow during video calls: how to find the culprit is the place to look if that is what you hit.

Quit Photos if you are not using it. Quitting Photos is ordinary and safe, and it frees what the app itself was using. The background analysis is separate and can carry on without it.

Restart if it never ends. If it has run hard for several days with no new photos, a restart clears most stalls.

Should you end it

You can, and macOS will start it again. A short pause is all you gain. Do not look for a way to disable it for good; there is no setting for that, and tampering with system background programs from Terminal is a way to break Photos features without gaining much.

Looking at it in Foreman

If you want to see how hard it is working, Foreman lists it on the Processes page as “Photos analysis”, with photoanalysisd beside it in grey. Click the CPU column to sort and it moves to the top when it is busy. The totals above each column show the whole Mac, so you can judge how much of the machine it has.

If it is quiet there, the problem is elsewhere, and you can stop worrying about Photos and look at the next row down instead.

If you want it to keep going but take less of the Mac while you work, Foreman can put it in Efficiency Mode. photoanalysisd runs under your own account (the User column shows this), and Foreman offers Efficiency Mode for any process that does, including parts of macOS like this one. It then runs at background priority, which on Apple silicon means the efficiency cores, with its disk use turned down. The analysis carries on, more slowly, and how much you notice depends on how busy the Mac is. Turn it off and it runs at full speed again at once. How to find out what’s running in the background on your Mac shows how to read the list.

When to worry

Usually never. Look closer if the Mac is hot or loud for days with Photos closed and no new pictures. Check free space in System Settings, General, Storage first, since a full disk slows everything. After that, a restart and a macOS update are the sensible next steps.

Quick answers

• Is it a virus? No. It belongs to Photos and macOS.
• Does it upload my faces? The analysis happens on the Mac.
• Can I speed it up? Leave the Mac awake and on power, and quit apps that compete with it.
• When does it stop? When the library has been analysed. New photos give it a little more to do.

The steps above need nothing extra. Foreman is $12 once, free for 24 hours, if you want to watch the row.