What is mdworker and Why They are on Mac

Written by Hassan Abbas

Have you guys ever wonder what the ‘mdworker’ process was on a Mac? mdworker is actually a short for ‘metadata server worker’ and if you’re still confused then don’t feel bad. mdworker is actually the core technology behind Mac OS X’s awesome search engine Spotlight. It spiders metadata from your Mac and its files and also creates a readable index. So that you can find things practically instantaneously through Spotlight (command-spacebar). In this article, we are going to talk about What is mdworker and Why They are on Mac. Let’s begin!

Why Are mdworker Using So Much RAM and CPU?

If you have recently migrated your files and apps from one Mac to another, then it’s normal for MDS and mdworker to take up a great deal of CPU power and memory as well. The same goes if you recently added a bunch of new files to your computer as well. The processes are both working in order to build an index of all your files, that is what will later power your fast searches.

How can you guys tell this is the case? Open Spotlight and then you will see the word “Indexing” next to a progress bar.

If you see that message, then you know that Spotlight is hard at work to create your index, and that’s the reason for the resource usage actually. This typically only takes a couple of hours, though this can vary depending on your hard drive and processor speed as well.

Spotlight is configured to not use up all of your resources. If you are doing something that’s processor intensive, then these processes should back off. However, if your Mac is left idle, and you are not on battery power, the Spotlight will feel free to use whatever resources are necessary in order to build the database.


mdworker is slowing my Mac with 60% CPU usage!

Yes, mdworker will sometimes cause your Mac to be slow and have high CPU usage as well. This is actually normal. You should just let it run until it is finished, and CPU usage will be back to normal then.

How long does the mdworker take to finish?

This is entirely dependent on the last time that your Mac filesystem was index and the number of new files since the indexing. If you just plugged in a loaded external hard drive, then expect it to take a while. 15 minutes to well over an hour are not uncommon amounts of time for mdworker to run actually. If you have a very large hard drive with a ton of data on it, then mdworker can take a long time to complete as each and every individual file is indexed.

Should You kill mdworker? What will happen if You kill mdworker?

No, you should not kill mdworker, because it’s doing you a service through indexing your Macs contents. If you do kill mdworker, then your Mac filesystem will not completely indexed and its searchability will be greatly reduced. Until mdworker runs again and completes full indexing as well. There is no serious problem with killing mdworker, We just not recommend actually.

Rebuild Your Spotlight Index

If these processes never seem to finish their job and are also constantly using your CPU and memory days after the indexing began. Then there’s a chance that your index is corrupt. Happily, you can fix problems like this by rebuilding the Spotlight index actually.

There are actually two main ways to do this. The first is to add your entire hard drive to the Excluded Locations list. Then re-add it. The second is to open the Terminal, then run these following command:

sudo mdutil -E /

Either way, your whole Spotlight index will be re-built, that  again you can see through pulling up Spotlight and looking for the word “Indexing” at the top left, alongside the progress bar.


Alright, That was all Folks! I hope you guys like this windows 7 disable fast user switching article and also find it helpful to you. Give us your feedback on it. Also if you guys have further queries and issues related to this article. Then let us know in the comments section below. We will get back to you shortly.

Have a Great Day!

Also See: How to Fix iMessage not Working on Mac

About the author

Hassan Abbas

Tech enthusiast with too many items on his wish-list and not nearly enough money! Specializing in all things tech, with a slight Apple bent he has been writing for various blogs for the best part of (too many) years

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