class Bundler::Installer

def install_in_parallel(size, standalone)
  name2spec = {}
  remains = {}
  enqueued = {}
  specs.each do |spec|
    name2spec[spec.name] = spec
    remains[spec.name] = true
  end
  worker_pool = ParallelWorkers.worker_pool size, lambda { |name, worker|
    spec = name2spec[name]
    message = install_gem_from_spec spec, standalone, worker
    { :name => spec.name, :post_install => message }
  }
  specs.each do |spec|
    deps = spec.dependencies.select { |dep| dep.type != :development }
    if deps.empty?
      worker_pool.enq spec.name
      enqueued[spec.name] = true
    end
  end
  until remains.empty?
    message = worker_pool.deq
    remains.delete message[:name]
    if message[:post_install]
      Installer.post_install_messages[message[:name]] = message[:post_install]
    end
    remains.keys.each do |name|
      next if enqueued[name]
      spec = name2spec[name]
      deps = spec.dependencies.select { |dep| remains[dep.name] and dep.type != :development }
      if deps.empty?
        worker_pool.enq name
        enqueued[name] = true
      end
    end
  end
  check_rubygems_cache_dir
  message
ensure
  worker_pool && worker_pool.stop
end