distributed lock aka ConditionVariable

distributed-lock.rb

# this requires the master branch of Celluloid

require 'celluloid'

class Worker
  include Celluloid

  def initialize(condition, number)
    @condition = condition
    @number = number

    async.work
  end

  def work
    Celluloid::Logger.info "worker #{@number.inspect} is waiting"
    @condition.wait
    Celluloid::Logger.info "worker #{@number.inspect} is working"
    sleep 1
    Celluloid::Logger.info "worker #{@number.inspect} is finished"
  ensure
    Celluloid::Logger.info "worker #{@number.inspect} is signalling"
    @condition.signal
    async.work
  end
end

condition = Celluloid::Condition.new

10.times do |number|
  Worker.new(condition, number)
end

# start the work
condition.signal

sleep

Gemfile

source "https://rubygems.org"

gem "celluloid", github: "celluloid/celluloid"