From: Michal Suchanek <hramrach@...>
Date: 2008-09-09T21:03:51+09:00
Subject: Re: Frustrated: System call timeouts

On 09/09/2008, Mikel Lindsaar <raasdnil@gmail.com> wrote:
> On Sun, Sep 7, 2008 at 12:42 AM, ara.t.howard <ara.t.howard@gmail.com> wrote:
>  > On Sep 6, 2008, at 3:43 AM, Mikel Lindsaar wrote:
>  >> Hello all,
>  >> I am having some (un)fun with timing out a database calls.
>
> > try this:
>  >       <snip>
>
> >       pid = Process.pid
>  >       signaler = IO.popen "ruby -e'sleep #{ seconds };
>  >       Process.kill(:TERM.to_s, #{ pid }) rescue nil'"
>  >       thread = Thread.current
>  >       handler = Signal.trap('TERM'){ thread.raise Error, seconds.to_s }
>  >       begin
>  >         block.call
>  >       ensure
>  >         Process.kill 'TERM', signaler.pid rescue nil
>  >         Signal.trap('TERM', handler)
>  >       end
>
>
> Ara, thank you _so_ much for this.
>
>  I would never have thought of spawning suicidal terminator ruby
>  processes to nuke my process :)  But works well.
>
>  There was a bit of delay (putting out some fires here over the past
>  two days) but I got to your code last night and this morning, and it
>  basically works... except it doesn't kill off the signaler threads
>  fully.
>
>  This is because two processes get made, first is the shell which then
>  creates the ruby -e "sleep..." blah thread.
>
>  The 'hack' I used to solve this is to replace the ensure block with:
>
>
>       ensure
>         Process.kill 'TERM', signaler.pid rescue nil
>
>         Process.kill('TERM', signaler.pid+1) rescue nil
>
>         Signal.trap('TERM', handler)
>       end
>
>
> But this obviously is insane as it assumes that no other processes get
>  started on the computer between sh starting up and it firing off the
>  ruby process.
>
>  the ps output looks like this:
>
>  $ ps -ef | grep ruby
>  rails     2153 2152 69 17:04 /usr/sbin/ruby1.8 /usr/bin/rake update:all
>  rails     2237 2153 69 17:04 sh -c ruby -e'sleep 40.0;?
>  Process.kill(:TERM.to_s, 2153) rescue nil'
>  rails     2238 2237 69 17:04 ruby -e'sleep 40.0;?
>  Process.kill(:TERM.to_s, 2153) rescue nil'
>
>  Any ideas on how to reliably find the PID of the ruby process that the
>  sh process created by IO.popen creates?
>

Since you are using popen anyway you can just have your ruby process
print it's PID when it starts, and read it in your terminator.

HTH

Michal