multi_download.rb

require 'open-uri'

class MultiDownload
  def initialize(*urls)
    @urls = urls
  end

  def to_h
    @urls.map { |url|
      Thread.new(url) do |url|
        content = open(url, &:read) rescue nil
        [url, content]
      end
    }.map(&:value).to_h
  end
end