kernel_task is using 100% CPU when waking from sleep

Since updating my 13" mid-2013 MacBook Air to Mavericks, there's this issue that's been happening when I wake the computer up from sleep. A proccess called kernel_task uses 100% CPU (a whole core) and hangs there until the computer is restarted. This doesn't make the computer unresponsive, but it kills battery life.


So far, I've tried the following:


1. Resetting SMC, NVRAM and PRAM: no effect.

2. Safe Boot: the issue doesn't happen.

3. Deleting old apps/plugins: issue persists.

4. Closing all apps doesn't solve issue after it takes place.

5. Repairing permissions: no effect.

6. Apple Diagnostics: no issue found in hardware.

7. No kernel extensions from third-parties are installed (there are 120 kext, according to Terminal, but they all come from Apple).

8. Everything is up to date.

9. Only external plugin installed is Flash.


Given these, I reckon it's something software-related. Any tips on solving this would be welcome — things to look for in Console logs would be greatly appreciated.

MacBook Air (13-inch Mid 2013), OS X Mavericks (10.9)

Posted on Oct 28, 2013 12:03 PM

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323 replies

Dec 10, 2013 3:42 AM in response to joeyjohnson

Forgot to mention..... what about killing the kernel_task process? Is this a big no no? Just curious, if restarting kills it, why not just kill it in Activity Monitor manually?


BTW - Safari crashes constantly too, and i had ONE browser tab open, THIS one!!!!! Quit unexpectedly, happens regularly. Anyone else have this since upgrading to mavericks?

Mail app also often can't display the reply,replyall,forward buttons which appear when you mouseover an email. Anyone else notice this? Works fine after quitting Mail, but reminds me of Windows 3.11 times!

Dec 10, 2013 4:19 AM in response to joeyjohnson

I have just done a restart, and when shutting down it gave me the grey screen "Computer shut down because of a problem". Weird. It started up again with an apple error which I submitted. I restarted again just for extra safety and it didn't error the second time. However having started on a fresh boot (reopen apps was ticked i should maybe add) i still have the kernel task using 778 MB of RAM and 100 threads. Is that normal? It's only using 1.2% of CPU now so maybe its fine now?

Dec 10, 2013 8:47 PM in response to joeyjohnson

The same stuff here. I don't think that problem is in headphones. I use headphones very rarely. But the kernel_task process seizes one core at 100% permanently. The only way to stop it - reboot.

Mavericks and new Retina MBP became a real nightmare for me. I was pretty happy with my 2011 Air with Lion except the screen. Ok, I fixed the screen problem with Retina, but got a new one, much more annoying...

Dec 13, 2013 2:50 AM in response to mac_12

Bought my rMBP (late 2013) 13" 2 weeks ago and I've noticed the same problem. Also it gets very hot when kernel_task eats up CPU. I've been wadding through miles of articles and discussions about this problem on various forums, and I believe the cause is in the OS itself. All we can do it wait until Apple releases a new fix.

Dec 13, 2013 12:53 PM in response to HalexPereira

I filed an official ticket with Apple on this. After sending them my logs, they just reponded claiming it to be a problem with the Drobo Driver and then they closed my ticket. Obviously, this isn't the case with everyone on this thread so I call BS. They pushing the blame to third parties because this was obviously never a problem before. But just wanted to share what they sent me.


Engineering has determined that this is an issue for a third party to resolve.

This is Drobo driver issue.

Dec 17, 2013 1:27 AM in response to corywright

Well mine isn't solved, it happens daily and causes me massive problems. As for formatting hard drive, glad it worked for you but no way I could or will do that. This is an Apple problem which they can sort on an update I am sure. There are many memory leaks and glitches in Mavericks and they just need sorting out thats all.


Note, everyone says Apple don't monitor these forums so it's no use talking about stuff on here, but for info, Apple clearly do monitor them (or at least censor them) as they removed my post when I mentioned Apple's share price. Maybe a touchy subject?! Either way, it's a shame they pay so much attention to censoring people who have gone off Apple lately, and very little to problems with the machines they sell.


I think it's clear to me and many others now, Apple is just another MS. The bigger you get, the less you have to listen to the real important people who buy your stuff. I am one less of those now.

Dec 17, 2013 2:42 PM in response to HalexPereira

Well just wanted to confirm. Having already gone back to 10.8, thought I would try a move to 10.9.1...no luck on my Macbook Air Mid 2013. Still getting 100%+ kernal_task after coming out of sleep.


It has to be software becuase if it was hardware I would see the issue in 10.8 but I dont.


A trip to the Apple store is on the cards after Xmas. Worst bug I've seen on any OS for a long long time.

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kernel_task is using 100% CPU when waking from sleep

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