Mdworker comes installed on Mac OS X and is part of the Spotlight search engine on your Mac computer. Mdworker is shortened for “metadata server worker.” The software goes through the meta data on your Mac computer and creates files that are indexed to find things when you use Spotlight search on OS X. Some blame mdworker for slower computer speeds and high Mac CPU usage because of mdworker. We’ve decided to answer some of the questions that you may have in regards to the mdworker process on Mac OS X.
What is mdworker?
Mdworker is part of Spotlight on Mac OS X Yosemite, Mavericks, Mountain Lion and Lion that is the foundation for the local search engine for files on your Mac computer.
Mdworker is slowing down my Mac CPU usage
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It has been reported by many that mdworker will sometimes cause your Mac to be slow and have high CPU usage. You can read more about this topic on the Apple Support Forum, here . You should just let it run until it’s finished, and CPU usage will be back to normal.
Should I kill mdworker? What happens if I kill mdworker?
It’s not recommended to kill mdworker, since it’s actually doing a service of indexing your Macs contents so you can easily access it in the future. If you do kill mdworker, your Mac filesystem will not be completely indexed and it’s searchability will be greatly reduced until mdworker runs again and completes a full indexing.
How can I stop mdworker or disable mdworker?
If you want to disable mdworker, this means that you would also need to disable Spotlight at the same time. The reason for this is because mdworker is part of Spotlight and only can be disabled if Spotlight is not running. Again, this is not recommended.
But if you want to know how to disable Spotlight so mdworker will stop working read these guides:
- Disable Spotlight Search on OS X Yosemite, Mavericks, Mountain Lion and Lion 
- Disable Spotlight Search on OS X 10.4 and 10.5 
How long does mdworker take to finish?
The time it takes mdworker to completed it’s task depends on when was the last time that your Mac filesystem was indexed and the amount of new files since indexing. If you just plugged in a loaded external hard drive, expect it to take a while. 15 minutes to well over an hour are not uncommon amounts of time for mdworker to run.
What about mds? Is this tied to mdworker?
Yes, mds is the parent metadata server that runs the child process mdworker, the two usually run concurrently.