Re: NSTask terminates when NSApplication exits
Re: NSTask terminates when NSApplication exits
- Subject: Re: NSTask terminates when NSApplication exits
- From: Keary Suska <email@hidden>
- Date: Thu, 19 Jan 2012 10:36:43 -0700
On Jan 18, 2012, at 2:27 PM, Ken Thomases wrote:
> On Jan 18, 2012, at 3:13 PM, Keary Suska wrote:
>
>> Any special handling of NSTask aside, Mac OS X uses Unix-based process control which closes all child processes when the parent is closed.
>
> No, that's not true. Where did you get that?
It has likely, as you point out, come from the entirely wrong orifice. I suspect I am confusing tis with system() and popen() calls, which I think have a dependency on the parent process' life, but I could be wrong about that too.
> Processes with a controlling terminal get a SIGHUP when that terminal is closed, and that will kill a naive process, but that wouldn't apply to subprocesses of GUI apps. Other than that, child processes are independent of their parent process.
>
>> Since your sub-program is Java you may be able to detach the child process.
>
> This doesn't make sense to me. What does being Java have to do with anything?
I meant as opposed to a Cocoa-based app. The Java runtime, AFAIK, does not have the same restrictions.
>> This is usually accomplished by the sub-program by executing a low-level fork(). It may need to be followed by an exec() to fully detach the process.
>
> Fork() creates the child subprocess as a near duplicate of the parent. Exec() replaces the process's image with a new one. This is the standard means of creating a subprocess running a new program, but doesn't particularly "detach" an already-existing subprocess from its parent (whatever that might mean).
Again, this might be my mistaking daemonizing pipe-to-subprocess, but I could be wrong about that too.
>> Note that you can't do this with Cocoa/Objective-C (at least Apple says you shouldn't…)
>
> You can fork() and exec() just fine. What you can't do is fork(), _not_ call exec(), and then do anything other than call POSIX async-cancel-safe APIs. That includes using high-level frameworks like Cocoa, Core Foundation, or the like.
This might also be where I recalled the necessity of fork-exec, but it has been some time since I wandered down that rabbit hole..
Sorry for the noise...
Keary Suska
Esoteritech, Inc.
"Demystifying technology for your home or business"
_______________________________________________
Cocoa-dev mailing list (email@hidden)
Please do not post admin requests or moderator comments to the list.
Contact the moderators at cocoa-dev-admins(at)lists.apple.com
Help/Unsubscribe/Update your Subscription:
This email sent to email@hidden