Rails - Sep 2009 - backgroundrb help needed!

I have what I thought would be a simple thing - we use backgroundrb to
watch a directory and process new files. We want to make sure that the
worker is running. I thought I could have a schedule that started the
worker every 5 minutes to make sure, but, it loads a new one each time
(not surprising).
Is there a way to make sure that there is one (and only one) of these
workers running at all times?

Hi Phil,

On Sat, 2009-09-05 at 04:41 -0700, phil wrote:
> I have what I thought would be a simple thing - we use backgroundrb to
> watch a directory and process new files. We want to make sure that the
> worker is running. I thought I could have a schedule that started the
> worker every 5 minutes to make sure, but, it loads a new one each time
> (not surprising).
> Is there a way to make sure that there is one (and only one) of these
> workers running at all times?
You''ll probably have better luck with this on the backgroundrb list.

http://backgroundrb.rubyforge.org/community/

HTH,
Bill

On Sep 5, 1:32 pm, bill walton
<bwalton...-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>
wrote:
> Hi Phil,
>
> On Sat, 2009-09-05 at 04:41 -0700, phil wrote:
> > I have what I thought would be a simple thing - we use backgroundrb to
> > watch a directory and process new files. We want to make sure that the
> > worker is running. I thought I could have a schedule that started the
> > worker every 5 minutes to make sure, but, it loads a new one each time
> > (not surprising).
> > Is there a way to make sure that there is one (and only one) of these
> > workers running at all times?
>
> You''ll probably have better luck with this on the backgroundrb
list.
>
> http://backgroundrb.rubyforge.org/community/
>
> HTH,
> Bill

BackgrounDRb or no, creating a  file containing the process''s PID, and
verifying that each time the process is started is the typical unixy
way to do this.  How I do it:

  def self.is_running?
    if File.exists? pidfile
      begin
        Process.kill 0, pid
        return true
      rescue Errno::EPERM
        puts "You don''t own this process."
        return true
      rescue Errno::ESRCH #pid doesn''t exist anymore
        delete_pidfile
      end
    end
    false
  end

  def self.delete_pidfile
    File.delete pidfile
  rescue
  end

  def self.pid
    File.read(pidfile).chomp.to_i rescue nil
  end

  def self.pidfile
    "path/to/background_process.pid"
  end


And of course just create the the appropriate file writing Process.pid
to it.