From: ara howard <ara.t.howard@...>
Date: 2008-02-02T13:22:05+09:00
Subject: Re: Child processes live after parent process is killed


On Feb 1, 2008, at 4:45 PM, Gary Wright wrote:

snip helpful explaintion...

> Ara, are you talking more about making sure that you are reaping  
> child processes?  The idea that your child process will outlive you  
> is quite common, for example when a daemon is started. It will often  
> outlive whatever started it.

well - i wasn't really talking about reaping, but killing ;-)

the only way i've found to *really* prevent a child from outliving  
it's parent is what slave.rb does internally which connect a lifeline  
from child to parent - that lifeline is a pipe.  the basic concept is  
(with syntax error i'm sure)

r, w = IO.pipe

fork do
   w.close

   Thread.new do
      begin
         r.read
      rescue Exception
         Kernel.exit
      end
   end

   child_stuff()

   exit
end

r.close


which is to say open a pipe, spawn a child, ensure the child exist if  
the pipe ever goes stale.  this makes a child die even if the parent  
gets 'kill -9'ed

cheers.

a @ http://codeforpeople.com/
--
we can deny everything, except that we have the possibility of being  
better. simply reflect on that.
h.h. the 14th dalai lama