David Rice

UPDATE check out the video of this bug in action. As you can see from this latest happening, there's no 3rd party software running. It's all Apple, so I guess now's the time you'd expect them to do something about it. Really annoyed with how this has been handled so far, i'm fuming.

So this post takes a diversion from my usual apple loving fanboyisms with a much darker and frustrated tone. This problem has been happening to me for ages, since I got my first Macbook pro (RIP). Now with a replacement I was hoping to have escaped from the computer gremlins but they just followed me right to the new machine.

After a bit of digging around I found this thread on the apple discussion forum and there seems to be a lot of people experiencing this issue. So please, if you're having this problem make some noise, join in the discussion or leave a comment here.

What Happens?

So I'll be developing away at my computer not suspecting a thing switching back and forth from iTerm, Texmate and Firefox. Maybe I'll even be listening to some tunes then BAM I'll go to switch back and the wee Application Switcher Bezel will stay on the screen. I can move the mouse and see it on screen but nothing else in the interface is responding. Madness! I have left the computer in this state for at least 15 minutes but it never recovers, the only thing to do is try and break it out of stasis!

From reading all of the posts on the apple discussion forum about this, it appears almost all the people experiencing it are apple laptop users with an external display! So use of an external display seems to be a crucial ingredient.

UPDATE So this has happened quite a couple of times since then but I have recently been collating the errors and whenever I disconnect the external display it will spew a bunch of errors *(one for every open application) * like the following to system.log if you open /Applications/Utilities/Console.app you can check for yourself.

Aug 19 14:17:07 starscream /System/Library/CoreServices/Dock.app/Contents/ \
MacOS/Dock: removeDisplayMapping: _CGSUnmapFramebuffer returns -536870206
Aug 19 14:17:07 starscream /Applications/Safari.app/Contents/MacOS/Safari: \ 
removeDisplayMapping: _CGSUnmapFramebuffer returns -536870206
...

SSH To The Rescue!

So I try the old favourite key command cmd+option+esc, nothing. I'm still wiggling the mouse trying to click, iTunes is still playing. Luckily there's another computer close to hand so I can SSH into the macbook and everything seems grand, I can run anything I want from the command line, sometimes running the following command will bring the computer back to life! only very occasionally though.

sudo killalll -9 Dock

This works I think because the Dock controls the applications switching functionality, but what generally happens is the Dock process is zombified. If that happens then I can kill any OSX gui application and it will be zombified too. The only way to get out of this mess I have found (without the aid of SSH) is to force shutdown or hard reset the macbook by pressing the power key for several seconds (and if that doesn't work hold cmd+shift+option at the same time).

Thankfully with SSH we can do things a bit more safely, but not without losing data!! agh! I have lost countless hours to this really really annoying bug in OSX. Sorry back to the point of this paragraph, having logged into the macbook from another computer I can issue the following command and it will always bring the macbook back to life instantly back to the login screen and loosing ALL unsaved data in open applications. So with that information, don't be issuing this command willy-nilly.

sudo killall -9 WindowServer

UPDATE: So as I said this has been happening a lot so I've been keeping the logs. After issuing this command I get a bunch of errors like the following in my system.log not generally for every application but they differ.

 Aug 19 14:27:53 starscream /System/Library/CoreServices/Dock.app/ \ 
 Contents/MacOS/Dock: kCGErrorCannotComplete : CGSDeviceLock: \
 Invalid device window
...
Aug 19 14:27:53 starscream /System/Library/CoreServices/Finder.app/ \ 
Contents/MacOS/Finder: kCGErrorInvalidConnection : \
CGSFlushWindowContentRegion: Invalid connection

Long Term Solution?

So far, I have been dismissed a number of times by Applecare Technical Support for having custom software installed on my macbook. Being a freelance developer, my machine is very important to me and if it crashes I lose time and money because of it, taking the time out to try and fix the computer is costly as it takes up at least the best part of a day to get everything migrated accross. So I have done all of the following at least once to try and fix this, but none have made an improvement;

• Reset PMU
• Reset PRAM
• Reset NVRAM
• Deleted /Users/username/Library/Caches and /Library/Caches
• Run the Apple Disk Utility Disk Repair and Repair Permissions
• Run the Apple Hardware Test tool - No Faults or Errors

I have also rebuilt the computer from scratch and updated to OSX 10.4.10 and it is still happening. Aghh! So unfortunately I don't see a fix for this in sight. On the thread I was talking about, several people report to being able to reproduce the issue from scratch and that Apple have been notified about it. So Apple, just stop pansying about, passing your customers off with lame excuses and blaming third party applications. Take responsibility for your own bugs and just f&*$ing fix it!