The short answer
photoanalysisd scans your photo library to recognise people and pets and build Memories; mediaanalysisd analyses photos and videos for things like text in images, visual search and scenes. They mostly work in the background when you aren't using Photos, and get busy after you import a lot of photos, turn on iCloud Photos or move to a new Mac. Apple says the scan can take up to a few days on a big library. Let it finish: leave the Mac idle and plugged in with Photos closed. Quitting them only pauses the work, because macOS starts them again.
On this page
What photoanalysisd and mediaanalysisd do
| Process | What it does |
|---|---|
photoanalysisd | Scans your photo library to recognise people and pets, and to build Memories and other suggestions in Photos. |
mediaanalysisd | Analyses photos and videos for things like text in images, visual search and scene detection. |
photoanalysisd- What it does
- Scans your photo library to recognise people and pets, and to build Memories and other suggestions in Photos.
mediaanalysisd- What it does
- Analyses photos and videos for things like text in images, visual search and scene detection.
Photos does this analysis on your Mac, so the work shows up as CPU use. Both processes are part of macOS and run from /System/Library/PrivateFrameworks.
When and why they get busy
Apple says Photos on a Mac detects people and pets as long as you aren't using the app, and that depending on your library's size and other background tasks, this can happen quickly or take up to a few days. The busy spells usually follow:
- Importing a lot of photos or videos.
- Turning on iCloud Photos on a Mac, when the library downloads and is analysed.
- Moving to a new Mac or restoring a library from a backup.
- A macOS update that brings new kinds of analysis.
Because the work waits while you use Photos, a big library takes longer to finish on a Mac that's rarely left idle.
How to check
top -l 2 -o cpu -n 30 -stats pid,command,cpu | grep -E "photoanalysisd|mediaanalysisd"In Activity Monitor, type “analysis” in the search field to see both processes. Busy for a few hours after a big import is normal. Their CPU use falls to near zero once the scan is done.
Is it safe to quit photoanalysisd?
It quits and restarts itself. Quitting it doesn't break anything, but it doesn't help either: macOS starts it again when there's work to do, and the scan carries on later. Quitting only pauses it, so the library takes longer to finish.
What to do about it
- Close Photos and leave the Mac idle and plugged in for a few hours, for example over lunch, so the scan can get through the library.
- Expect a large library to take a few days of idle time, as Apple says.
- If it stays busy for days with no new photos, restart the Mac and give it an idle hour.
- If it still never settles, Apple's Photos Repair Library tool can fix a damaged library: back up your library first, then hold Command and Option while you open Photos.
The faster way: “What is this?” in iKnowMyMac
iKnowMyMac explains this inside the app. Every process row has a “What is this?” action that says what the process is, whether it's safe to quit, why it's busy right now and the one fix. For the Photos processes, it adds up their CPU and says whether Photos is analysing your library right now.