dir = Path[ENV.fetch("PROCIO_DIR", "/proc")]
result = {} of String => Array(UInt64)
time = Time.utc.to_s("%s%9N")

Dir.children(dir).each do |entry|
  next unless (entry =~ /^\d+$/) && File.directory?(dir/entry)

  begin
    comm = File.read("#{dir}/#{entry}/comm").chomp
    result[comm] ||= [0.to_u64, 0.to_u64]

    File.read_lines("#{dir}/#{entry}/io").each do |line|
      if line.starts_with?("read_bytes: ")
        result[comm][0] += line.split(" ").last.to_u64
      elsif line.starts_with?("write_bytes: ")
        result[comm][1] += line.split(" ").last.to_u64
      end
    end
  rescue File::NotFoundError
    # process might already have exited
  end
end

result.each do |comm, (r, w)|
  if r > 0 && w > 0
    puts %(procio,comm="#{comm}" read_bytes=#{r},write_bytes=#{w} #{time})
  end
end