macOS process library
What is mdworker on Mac?
mdworker is the Spotlight worker process that opens files and pulls out their contents and metadata for the search index. On current macOS, Activity Monitor usually shows it as mdworker_shared, often several copies at once.
- Part of
- Spotlight’s metadata worker, started by macOS’s indexing service.
- Safe?
- Yes. It is part of Spotlight and runs on every Mac.
- Can I quit it?
- You can, but there’s little point: workers are short-lived and Spotlight starts new ones as soon as files change.
The short answer
Seeing mdworker_shared is normal, and so are several copies. They spike when lots of files change at once: after an update, a big copy, cloning a project, or installing dependencies. Indexing usually finishes on its own. If a folder churns constantly and you never search it, excluding it from Spotlight is the lasting fix.
Normal use
What mdworker usually looks like.
Most of the time each mdworker_shared process uses little CPU and tens of megabytes of memory, and they come and go quickly as files change.
After a macOS update, a migration, or connecting a new drive, Spotlight may reindex a lot at once. Several workers can run hard for a while, together with mds_stores, which writes the index.
Why mdworker uses so much CPU or memory
- Lots of files changing
Unzipping archives, copying folders, or syncing a cloud drive gives Spotlight many new files to read.
- Development folders
Installing dependencies, building, or switching git branches can create or touch thousands of files in folders like
node_modulesand build outputs. - A macOS update or new drive
Updates and newly connected volumes can trigger a large reindex.
- A file that’s hard to index
Occasionally a damaged or unusual file makes a worker struggle. Spotlight usually moves on, but it can cause a stretch of high CPU.
How to calm mdworker down
Start at the top. Each step is more disruptive than the one before.
- Let indexing finish
If you just updated, migrated, or copied a lot of files, give it time. Run
mdutil -s /in Terminal to see whether indexing is enabled for your startup disk. - Exclude busy folders
In System Settings → Spotlight (or Siri & Spotlight), click Search Privacy (or Spotlight Privacy) and add folders you never search, such as build output or large dependency folders.
- Pause big file operations
If a sync or build is running in a loop, stop it and see whether the workers calm down.
- Rebuild the Spotlight index
If search results are wrong or indexing never ends, add your disk to the Search Privacy list, wait a few seconds, then remove it. Spotlight reindexes from scratch, which takes a while.
- Restart your Mac
A restart clears stuck workers. Save your work first.
Seeing it in Spare
Find what it’s reacting to.
mdworker_shared often spikes because of something you did a moment ago. Spare shows development projects grouped by folder, with their ports, next to your apps and AI agents, so you can connect a burst of indexing to the build or install that caused it.
Spare treats macOS processes like mdworker_shared as system tasks and never offers to stop them. Spare doesn’t monitor disk activity.
Common questions
About mdworker
What is mdworker_shared?
It is the current name for Spotlight’s worker process. It reads files and hands what it finds to the Spotlight index.
Why are there so many mdworker_shared processes?
Spotlight runs several workers in parallel and starts and stops them as needed. Many copies is normal.
Can I turn off mdworker?
Not without turning off Spotlight indexing. Excluding specific folders in Search Privacy is a gentler way to reduce its work.
Is mdworker_shared a virus?
No. It lives inside macOS’s protected CoreServices framework and is part of Spotlight.
Related processes
Sources: Apple: Rebuild the Spotlight index on your Mac, mdworker(8) man page, macOS. Reviewed October 6, 2026.
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