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I am (trying to be) running Xcode 4.3.2. on Lion 10.7.3

I noticed that when I stop watching Xcode and walk away from the computer for a while (like half an hour or so), Xcode in the mean time stopped running and has to be started again.

I read a lot about Xcode on Lion being unstable. Is that what is happening to me? Is it that unstable?

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Are you running Xcode with any projects, files, etc open when it quits or is it just Xcode is open, you come back to it and it is no longer open without a trace? – MrDaniel Apr 16 '12 at 14:41
All it did was installing the command line tools. For some reason it had to download them and that took a while. I let it be with no window open. Twice I found it closed without a trace and the command line tools not installed. (They had to be downloaded again from the beginning.) – Andrew J. Brehm Apr 16 '12 at 14:45
up vote 2 down vote accepted

This may be the built in "undocumented" to non-developers feature of Lion called Automatic Termination that is causing Xcode to quit when you don't want it to.

As noted in "Lion Is a Quitter"

Lion will quit your running applications behind your back if it decides it needs the resources, and if you don’t appear to be using them. The heuristic for determining whether an application is “in use” is very conservative: it must not be the active application, it must have no visible, non-minimized windows — and, of course, it must explicitly support Automatic Termination.

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That is ridiculous. I don't mean your answer, but the design decision. I think Apple have lost their mind! – Andrew J. Brehm Apr 16 '12 at 15:16
I just notice that Xcode has quit again... – Andrew J. Brehm Apr 16 '12 at 15:16
That particular Lion defect appears to be the reason for the weird behaviour. Any idea how I can repair this? – Andrew J. Brehm Apr 16 '12 at 15:22
It's the automatic termination all right. When Xcode is just downloading stuff, no window is open and that means Xcode is ready for auto termination at Lion's pleasure. Only the third time downloading the command line tools worked because I left the Preferences window open that time. – Andrew J. Brehm Apr 16 '12 at 15:30
@AndrewJ.Brehm The auto-termination is supposed to work with the saving of state on quit so unused programs quit (and then take no processor or memory instead of some); when the user relaunches the program, it resumes as if it had never quit. This is a bug in Xcode; I think the auto-termination feature is a good idea. My parents leave apps open all the time and get confused when their iMac gets slow. Auto-termination keeps their machine fast and they don't have to think about quitting every app they're not using ringt now. – CajunLuke Apr 16 '12 at 19:07

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