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comp.lang.ruby

Killing a Process started with Kernel.system

Martin aus Chemnitz

5/24/2005 5:40:00 AM

Hi!

I know, this question was asked a dozen times, but I can't believe that
Ruby does not offer a suitable solution. I therefore write this posting
more in the spirit of an urgent feature request.

Under Windows, I want to start an external program and kill it on
exitting my Ruby script.

begin
$t = Thread.new { system("everlasting") }
...
ensure
$t.kill
end

does not stop the everlasting program, it stops $t, not its child
processes. Such a command is urgently needed!

Yukihiro Matsumoto writes in
<1052988371.738185.28868.nullmailer@picachu.netlab.jp>:
> If you want to kill child processes when the thread is down,
>
> th = Thread.new{
> Thread.current[:children] = []
> begin
> ... add child processes to Thread.current[:children]
> ensure
> Process.kill("TERM", *Thread.current[:children])
> end
> }
but I think I can't get the PID of a system call either.

I would be glad if such a feature could be implemented. (Or, of course,
if anyone can tell me suitable solution.)

Martin
5 Answers

Bill Kelly

5/24/2005 6:31:00 AM

0

From: "Martin aus Chemnitz" <MartinAusChemnitz@gmx.net>
>
> Under Windows, I want to start an external program and kill it on
> exitting my Ruby script.
>
> begin
> $t = Thread.new { system("everlasting") }
> ...
> ensure
> $t.kill
> end
>
> does not stop the everlasting program, it stops $t, not its child
> processes. Such a command is urgently needed!
>
> Yukihiro Matsumoto writes in
> <1052988371.738185.28868.nullmailer@picachu.netlab.jp>:
> > If you want to kill child processes when the thread is down,
> >
> > th = Thread.new{
> > Thread.current[:children] = []
> > begin
> > ... add child processes to Thread.current[:children]
> > ensure
> > Process.kill("TERM", *Thread.current[:children])
> > end
> > }
> but I think I can't get the PID of a system call either.
>
> I would be glad if such a feature could be implemented. (Or, of course,
> if anyone can tell me suitable solution.)

I'm guessing the problem is your "everlasting" program
spawns itself in the manner of rubyw.exe, where it
does sort of the windows equivalent of daemonizing
itself. So your system("everlasting") call returns
immediately, and your "everlasting.exe" is launching
as a separate process, for which you have no way (that
I know of) of obtaining the PID.

Maybe a windows guru can help. I'm doubtful this is
a behavior ruby has any control over. If I understand
correctly, you may be up against a fundamental problem
with Windows' way of launching non-console applications.
(I guess there must be some way to solve it, if one
were to write an extension, since certainly the Visual
Studio debugger is able to launch non-console
applications but obtain their PID's.)


Sorry I can't be of more help,

Regards,

Bill

Nakada, Nobuyoshi

5/24/2005 6:38:00 AM

0

Hi,

At Tue, 24 May 2005 14:40:17 +0900,
Martin aus Chemnitz wrote in [ruby-talk:143491]:
> Yukihiro Matsumoto writes in
> <1052988371.738185.28868.nullmailer@picachu.netlab.jp>:
> > If you want to kill child processes when the thread is down,
> >
> > th = Thread.new{
> > Thread.current[:children] = []
> > begin
> > ... add child processes to Thread.current[:children]
> > ensure
> > Process.kill("TERM", *Thread.current[:children])
> > end
> > }
> but I think I can't get the PID of a system call either.

Fundamentally, since Kernel.system doesn't finish until the child
process exits, so PID can not be available.

> I would be glad if such a feature could be implemented. (Or, of course,
> if anyone can tell me suitable solution.)

In 1.9, Kernel.spawn (or Process.spawn) does it.

--
Nobu Nakada

Nakada, Nobuyoshi

5/24/2005 6:40:00 AM

0

Hi,

At Tue, 24 May 2005 14:40:17 +0900,
Martin aus Chemnitz wrote in [ruby-talk:143491]:
> Yukihiro Matsumoto writes in
> <1052988371.738185.28868.nullmailer@picachu.netlab.jp>:
> > If you want to kill child processes when the thread is down,
> >
> > th = Thread.new{
> > Thread.current[:children] = []
> > begin
> > ... add child processes to Thread.current[:children]
> > ensure
> > Process.kill("TERM", *Thread.current[:children])
> > end
> > }
> but I think I can't get the PID of a system call either.

Fundamentally, since Kernel.system doesn't finish until the child
process exits, so PID can not be available.

> I would be glad if such a feature could be implemented. (Or, of course,
> if anyone can tell me suitable solution.)

In 1.9, Kernel.spawn (or Process.spawn) does it.

--
Nobu Nakada

Gavin Kistner

5/24/2005 12:35:00 PM

0

On May 23, 2005, at 11:40 PM, Martin aus Chemnitz wrote:
> Under Windows, I want to start an external program and kill it on
> exitting my Ruby script.
>
> begin
> $t = Thread.new { system("everlasting") }
> ...
> ensure
> $t.kill
> end
>
> does not stop the everlasting program, it stops $t, not its child
> processes. Such a command is urgently needed!

Here's a way to kill any process using Win32OLE:

require 'win32ole'

class WIN32OLE
def to_a
a = []; self.each{ |p| a<<p }; a
end
end

# Find the process for the player
mgmt = WIN32OLE.connect('winmgmts:\\\\.')
process = mgmt.InstancesOf("win32_process").to_a.find{ |proc|
proc.name =~ /myapp.exe/ }
process.Terminate

Ara.T.Howard

5/24/2005 2:07:00 PM

0