gistfile1.rb

require 'java'

java_import java.util.concurrent.Executors
java_import java.lang.System

def benchmark(&work)
  before = System.nanoTime
  work.call
  after = System.nanoTime

  p "That took #{(after - before)/1E9}s"
end

class Something
  attr_reader :value

  def initialize(value)
    @queue = Executors.newSingleThreadExecutor
    @value = value
    @lock = java.util.concurrent.locks.ReentrantLock.new
  end

  def inc
    @queue.execute { @value += 1 }
  end

  def inc_locked
    @lock.lock
    @value += 1
    @lock.unlock
  end
  
  def finalize
    @queue.shutdown
  end
end


s = Something.new(0)

# Async :(
benchmark do
  workers = 3.times.map { Thread.new { 1E3.to_i.times { s.inc } } }
  workers.map { |w| w.join }
end

# Locked :)
benchmark do
  workers = 3.times.map { Thread.new { 1E3.to_i.times { s.inc_locked } } }
  workers.map { |w| w.join }
end