Asp Forum - killing off a process tree

dmatrix00d

7/11/2006 9:47:00 PM

Is there a command in ruby that when given the pid , it will terminate
all children processes of that pid including itself.

It seems that Process.kill(9, pid) only kills the parent and not the
children.

thanks

9 Answers

Ara.T.Howard

7/11/2006 10:01:00 PM

Name Name

7/12/2006 3:33:00 AM

I don't understand what you mean. Can you reexplain. sorry

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Martin Lukasik

7/12/2006 9:45:00 AM

> Is there a command in ruby that when given the pid , it will terminate
> all children processes of that pid including itself.
>
> It seems that Process.kill(9, pid) only kills the parent and not the
> children.

[root@aster aster]# kill -l
1) SIGHUP 2) SIGINT 3) SIGQUIT 4) SIGILL
5) SIGTRAP 6) SIGABRT 7) SIGBUS 8) SIGFPE
9) SIGKILL 10) SIGUSR1 11) SIGSEGV 12) SIGUSR2
13) SIGPIPE 14) SIGALRM 15) SIGTERM 17) SIGCHLD
18) SIGCONT 19) SIGSTOP 20) SIGTSTP 21) SIGTTIN
22) SIGTTOU 23) SIGURG 24) SIGXCPU 25) SIGXFSZ
26) SIGVTALRM 27) SIGPROF 28) SIGWINCH 29) SIGIO
30) SIGPWR 31) SIGSYS 34) SIGRTMIN 35) SIGRTMIN+1
36) SIGRTMIN+2 37) SIGRTMIN+3 38) SIGRTMIN+4 39) SIGRTMIN+5
40) SIGRTMIN+6 41) SIGRTMIN+7 42) SIGRTMIN+8 43) SIGRTMIN+9
44) SIGRTMIN+10 45) SIGRTMIN+11 46) SIGRTMIN+12 47) SIGRTMIN+13
48) SIGRTMIN+14 49) SIGRTMIN+15 50) SIGRTMAX-14 51) SIGRTMAX-13
52) SIGRTMAX-12 53) SIGRTMAX-11 54) SIGRTMAX-10 55) SIGRTMAX-9
56) SIGRTMAX-8 57) SIGRTMAX-7 58) SIGRTMAX-6 59) SIGRTMAX-5
60) SIGRTMAX-4 61) SIGRTMAX-3 62) SIGRTMAX-2 63) SIGRTMAX-1
64) SIGRTMAX

You are killing process, so you will have "zombies" left sometimes.
Try sig 15 instead of using 9. Try sigquit (3) as well...

m.

Francis Cianfrocca

7/12/2006 12:47:00 PM

Erich Lin wrote:
> Is there a command in ruby that when given the pid , it will terminate
> all children processes of that pid including itself.
>
> It seems that Process.kill(9, pid) only kills the parent and not the
> children.
>
>
> thanks

I'll assume you're talking about Unix, even though when this question
comes up people are usually looking for something that works on Windows
too. The following is only meaningful on Unix.

There's no universally-valid assumption about the relationship between a
process and the processes that it forks (and the processes that the
children fork in turn). (In particular, processes invoked in the
foreground of a shell will have a relationship with their children and
grandchildren, but it's different with processes created by other
means.)

Try making your parent process a process-group leader. There are Ruby
APIs to support this- just make sure you call them in both the parent
and the child to avoid race conditions. In the child, set the process
group leader after the fork but before the exec. Now if you send a
signal to -n (where n is the pid of your parent process), then all of
the children will get the signal too.

Signal 9 is very unfriendly. Don't use it unless it's an emergency. Use
SIGINT or SIGTERM instead.

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Name Name

7/12/2006 1:43:00 PM

dmatrix00d

7/12/2006 1:47:00 PM

I would like this to be portable on both linux and windows. Seemingly
you can only use 0-9 on windows, and none of them seems to kill a tree.

Some of them are even undefined signals. Can you do this process-group

leader thing on windows? Also , I would like to clarify my original
question. I meant taht I would call a parent process to open, which is

some program. And that program can POTENTIALLY open up other children
processes. The thing is I only have the pid of the parent, and when I
kill the parent, only the parent will die. Is there a way that I can
kill the parent and the children that it sprang (which I did not
provide
the exec code for since they were provided by the parent itself that I
did not code).

Martin Lukasik wrote:
> > Is there a command in ruby that when given the pid , it will terminate
> > all children processes of that pid including itself.
> >
> > It seems that Process.kill(9, pid) only kills the parent and not the
> > children.
>
>
> [root@aster aster]# kill -l
> 1) SIGHUP 2) SIGINT 3) SIGQUIT 4) SIGILL
> 5) SIGTRAP 6) SIGABRT 7) SIGBUS 8) SIGFPE
> 9) SIGKILL 10) SIGUSR1 11) SIGSEGV 12) SIGUSR2
> 13) SIGPIPE 14) SIGALRM 15) SIGTERM 17) SIGCHLD
> 18) SIGCONT 19) SIGSTOP 20) SIGTSTP 21) SIGTTIN
> 22) SIGTTOU 23) SIGURG 24) SIGXCPU 25) SIGXFSZ
> 26) SIGVTALRM 27) SIGPROF 28) SIGWINCH 29) SIGIO
> 30) SIGPWR 31) SIGSYS 34) SIGRTMIN 35) SIGRTMIN+1
> 36) SIGRTMIN+2 37) SIGRTMIN+3 38) SIGRTMIN+4 39) SIGRTMIN+5
> 40) SIGRTMIN+6 41) SIGRTMIN+7 42) SIGRTMIN+8 43) SIGRTMIN+9
> 44) SIGRTMIN+10 45) SIGRTMIN+11 46) SIGRTMIN+12 47) SIGRTMIN+13
> 48) SIGRTMIN+14 49) SIGRTMIN+15 50) SIGRTMAX-14 51) SIGRTMAX-13
> 52) SIGRTMAX-12 53) SIGRTMAX-11 54) SIGRTMAX-10 55) SIGRTMAX-9
> 56) SIGRTMAX-8 57) SIGRTMAX-7 58) SIGRTMAX-6 59) SIGRTMAX-5
> 60) SIGRTMAX-4 61) SIGRTMAX-3 62) SIGRTMAX-2 63) SIGRTMAX-1
> 64) SIGRTMAX
>
> You are killing process, so you will have "zombies" left sometimes.
> Try sig 15 instead of using 9. Try sigquit (3) as well...
>
> m.

Ara.T.Howard

7/12/2006 2:03:00 PM

Douglas McNaught

7/12/2006 2:12:00 PM

"Erich Lin" <dmatrix00d@gmail.com> writes:

> I meant taht I would call a parent process to open, which is some
> program. And that program can POTENTIALLY open up other children
> processes. The thing is I only have the pid of the parent, and when
> I kill the parent, only the parent will die. Is there a way that I
> can kill the parent and the children that it sprang (which I did not
> provide the exec code for since they were provided by the parent
> itself that I did not code).

I don't think you can do this in the general case on Unix unless you
use ptrace(), which you really don't want to do. A process can only
know its immediate children. If you call setsid() in the child after
the fork(), and if the program you exec() doesn't do any
session-management calls (setsid(), setpgrp()) itself, then it will
probably work to call 'kill(-N, SIGTERM)' where N is the PID of your
child process (which is the parent of the other processes). If the
program you're calling does setsid() or setpgrp() on its own, you will
probably lose.

This session and process group stuff will bend your brain--it's not
simple at all. I have no idea whether you can do what you're looking
for on Windows, though you might be able to using the POSIX
extensions.

-Doug

Berger, Daniel

7/13/2006 2:32:00 PM

Douglas McNaught wrote:
> "Erich Lin" <dmatrix00d@gmail.com> writes:
>
>> I meant taht I would call a parent process to open, which is some
>> program. And that program can POTENTIALLY open up other children
>> processes. The thing is I only have the pid of the parent, and when
>> I kill the parent, only the parent will die. Is there a way that I
>> can kill the parent and the children that it sprang (which I did not
>> provide the exec code for since they were provided by the parent
>> itself that I did not code).
>
> I don't think you can do this in the general case on Unix unless you
> use ptrace(), which you really don't want to do. A process can only
> know its immediate children. If you call setsid() in the child after
> the fork(), and if the program you exec() doesn't do any
> session-management calls (setsid(), setpgrp()) itself, then it will
> probably work to call 'kill(-N, SIGTERM)' where N is the PID of your
> child process (which is the parent of the other processes). If the
> program you're calling does setsid() or setpgrp() on its own, you will
> probably lose.
>
> This session and process group stuff will bend your brain--it's not
> simple at all. I have no idea whether you can do what you're looking
> for on Windows, though you might be able to using the POSIX
> extensions.
>
> -Doug
>

Note that there is Process.sigsend if you have the proc-wait3 package:

require 'proc/wait3'

Process.sigsend(Process::P_PGID, gid, 'TERM')

This will not work on MS Windows, however. For Windows you'll have to use
sys-proctable and manually check for the ppid member value.

Regards,

Dan

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comp.lang.ruby

killing off a process tree

dmatrix00d

Ara.T.Howard

Name Name

Martin Lukasik

Francis Cianfrocca

Name Name

dmatrix00d

Ara.T.Howard

Douglas McNaught

Berger, Daniel

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