t.rb

require 'rubygems'
require 'ruote'

engine = Ruote::Engine.new(Ruote::Worker.new(Ruote::HashStorage.new))

pdef = Ruote.process_definition do
  alpha
end

class Ruote::StorageParticipant
  def next
    find { |wi| wi.fields['__reserved__'] != true }
  end
  def reserve(wi)
    wi.fields['__reserved__'] = true
    update(wi)
  end
  def reserve_next
    wi = self.next
    reserve(wi)
    wi
  end
end

engine.register_participant 'alpha', Ruote::StorageParticipant

5.times do
  engine.launch(pdef)
end

sleep 3

p engine.storage_participant.reserve_next