macOS processes › Spotlight and search
What is mdworker on Mac?
mdworker is a Spotlight helper that opens files and extracts what Spotlight indexes, like text, titles, authors and dates. Current macOS mostly uses mdworker_shared for this, but mdworker still ships and can appear.
What it does
Each file format needs an importer, a small plug-in that knows how to read it. mdworker runs those importers for mds. It's short-lived: it starts, works through a batch of files, and exits.
Why it gets busy
- A slow or buggy third-party Spotlight importer installed by an app.
- Many large documents, like PDFs, being indexed at once.
Why is mdworker using so much CPU?
mdworker uses CPU while it reads files for Spotlight. Constant use often traces back to a third-party importer struggling with certain files, and mdimport -L lists the importers you have.
Is it safe to quit?
mds starts another worker when there's more to index, so quitting one only delays that batch.
How to calm it down
- Let it finish its batch. It exits by itself.
- If one app's files are always involved, update that app, since it may install its own Spotlight importer.
- Run
mdimport -Lin Terminal to list the Spotlight importers on your Mac. Third-party ones live outside /System.
In SystemWatch
SystemWatch shows mdworker as Spotlight indexing, so an odd process name becomes something you recognize, and History shows when indexing ran.
