From: john casu <casuj@...01.TheWorld.com>
Date: 2005-07-23T17:10:58+09:00
Subject: Catching DRb exceptions ??


I have a simple problem.
I want to launch a DRb server from my program (in my case a parallel MPI program, 
where the zero rank process is the actual DRb server), and then connect to it.

If I place a long enough sleep before invoking DRbObject.new, then everything
is groovy, and things proceed as intended.  If I don't, then I get a DRbConnError
exception when DRB tries to connect to the server (which hasn't started up yet)

My problem is that I am unable to catch the exception that DRbObject.new raises
(i.e, I never see the "got exception" message in the attached code below), and 
hence I am at the mercy of race conditions for this to work in a consistent way 
without an excessively long sleep.

Can anyone please point out to me where I'm being a moron, and what I'm doing wrong ?  
I'm running ruby-1.8.3 on Fedora Core 4 Linux.

Thanks,

john c.

-------------------------------------------------------------------

require 'drb'
require 'thread'

foo_serve = Thread.new do
  system("/bin/bash -c \"foo_server\"")
end


# sleep 5.0

DRb.start_service
foo = nil

until (foo)
  begin
    foo = DRbObject.new(nil, 'druby://hobbes:7777')
  rescue StandardError, DRbConnError
    p "got exception"
  ensure
    sleep 0.05 
  end
end

puts foo.call_remote_foo(0, "run")
puts foo.call_remote_foo(0, "exit")