Very Computer

Hi NG!
Can someone give me a good reason for the fact that SIGKILL (supposed
to instantly kill an app as it can't be catched) can't kill a process
listed with status D in `ps ax` that is, an IO sleep? Why having
developed that signal if it can't kill everything it comes across?
Related question: Is it possible to force init to read the return code
of a zombie even if its parent process is still there but is stuck
e.g. in an IO sleep?
Thanks!
Bernd Haller.

0 spat:

Quote:> Can someone give me a good reason for the fact that SIGKILL (supposed
> to instantly kill an app as it can't be catched) can't kill a process
> listed with status D in `ps ax` that is, an IO sleep? Why having
> developed that signal if it can't kill everything it comes across?

because that process is in a system call - it'll be killed once
the call returns.

--
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
 Michael J. Tobler: motorcyclist, surfer,  #    Black holes result
 skydiver, and author: "Inside Linux",     #   when God divides the
 "C++ HowTo", "C++ Unleashed"              #     universe by zero

Quote:> > Can someone give me a good reason for the fact that SIGKILL (supposed
> > to instantly kill an app as it can't be catched) can't kill a process
> > listed with status D in `ps ax` that is, an IO sleep? Why having
> > developed that signal if it can't kill everything it comes across?

> because that process is in a system call - it'll be killed once
> the call returns.

yes but if the system call is blocking or has a very long timeout,
there must be some sort of 'emergency break' to tell the kernel that
this or that process has gone mad. Just imagine a beta software or a
debugging session. The user should always have the last word, we're
not running windows here ;)
Bernd Haller

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... /usr/src/linux/...   :)

--
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
 Michael J. Tobler: motorcyclist, surfer,  #    Black holes result
 skydiver, and author: "Inside Linux",     #   when God divides the  
 "C++ HowTo", "C++ Unleashed"              #     universe by zero

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