Why is mdworker using so much CPU?

mdworker is the Spotlight indexing worker process. High CPU during reindexing is normal and temporary.

Can I stop Spotlight indexing?

Yes, sudo mdutil -i off / disables indexing. But Spotlight search will not work until you re-enable it with sudo mdutil -i on /.

Mac Spotlight Reindex — Search Not Working & Index Corruption

Warningsystem

Overview

Fix macOS Spotlight issues including search returning no results, index corruption, high CPU usage from mdworker, and missing files in search results.

Key Details

Spotlight uses the mdworker and mds processes to index file content and metadata
A corrupted index causes missing search results or Spotlight showing outdated information
After macOS updates, Spotlight may need to reindex which temporarily uses high CPU
The .Spotlight-V100 folder at the volume root contains the index data
Privacy settings can exclude folders from Spotlight indexing

Common Causes

Corrupted Spotlight index from disk errors or interrupted indexing
macOS update triggering a full reindex
External drive index not updating properly
Privacy settings accidentally excluding important folders
Third-party software (Parallels, VM software) corrupting index

Steps

1Force reindex via Terminal: sudo mdutil -E / (erases and rebuilds index for boot volume)
2Force reindex specific volume: sudo mdutil -E /Volumes/DriveName
3Check indexing status: mdutil -s /
4If mdworker uses high CPU, wait for reindex to complete (can take several hours)
5Check Privacy exclusions: System Settings > Siri & Spotlight > Spotlight Privacy — remove accidental exclusions