Very high memory and CPU usage by the OS X Dock

Question

I have a very annoying problem with the Dock process - after more than a few hours of uptime, the memory usage will spike to more RAM than I have. The process will begin to thrash the hard drive at the maximum speed that it can (according to iotop), and it will regularly use more than 100% of CPU, which I guess means that it's using more than one core at the moment. The number of threads in use ranges between 5 and 12.

Even though I have 12gb of RAM, I regularly start running into the swap file, and I have to kill the Dock process. This resets the amount of memory that it uses to about 60mb, but within minutes, it will be taking up more than a gigabyte again.

Because of the high memory usage, CPU usage and swapping, this regularly makes my computer entirely unusable. Given that this is my main work machine, I will have to probably reinstall it soon if I cannot find a solution, and I can only hope that reinstalling it will actually fix the problem. Has anyone encountered a similar issue before?

Solution 1

If you are using Parallels Desktop 6, this article may apply :
Dock using 100% CPU after OS X 10.6.8 update for Parallels 6 users.
The details can be found in this Parallels KB article:
Mac Dock consuming 100% of CPU core after upgrade to Mac OS X 10.6.8.

Adobe Updater in the dock is also cited as a possible cause.

To completely reset the dock back to the original factory settings, remove the files "com.apple.Dock.plist" and "com.apple.Dock.db" from your /username/Library/Preferences/ folder, and then log out and back in again. Be sure to write down what you have in the Dock, so you can set it up again just as you had it.

Solution 2

Another cause for Dock to consume >2GB real memory...

I had selected a set of photos to cycle as my desktop background. Some fo the images were rather large TIF images. This caused Dock to consume extremely large amounts of memory and CPU. Since the problem depended on image, it would seem to come and go and was therefore, hard to tie down.

Reverting to a single, normal sized JPG solved the problem completely.

Solution 3

This can also occur with VMware Fusion 4.1.1. If I quit VMware, the Dock process returns to normal CPU usage within a few seconds.

Solution 4

I recently discovered consistent ~20% CPU usage on my MacBook Air was caused by the "Change picture" setting being enabled and set to "Every 5 seconds".

Disabling that setting caused the Dock process to drop to virtually idle.

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Comments

[Steve Rukuts]

Thanks for the tips. While I had found the Parellels article in my searching, I didn't realise I still had it installed after dropping it in favour of VMWare Fusion. I performed the steps as directed, but it didn't seem to have any effect. Also, there is no mention of very high RAM or IO usage in the article. I'm going to try the other steps, the issues should manifest in a day or two if resetting the dock doesn't help. Thanks for your time!

[Steve Rukuts]

Interestingly, as soon as I quit VMWare to restart, the Dock process started behaving normally again. I have now found this issue related to VMWware and Dock CPU/memory usage: communities.vmware.com/thread/333119?start=0&tstart=0

[harrymc]

It seems like a good article, and it is worthwhile to try out all the mentioned solutions. Did you try resetting the dock as in my answer ?

[Steve Rukuts]

The suggested workaround is to turn off Shared Folders until VMWare fix this. I'm going to trial this for a couple of days.

[Steve Rukuts]

Turning off Shared Folders worked, all is good with the world. Thanks for prodding me on to that train of thought; enjoy some delicious reputation!