config.ru

# rackup -s puma
require 'puma' # thin does some weird caching

run proc { |env|
  body = Enumerator.new do |socket|
    socket << " "*1024 # Browsers wait for time or big data chunk
    
    5.times do
      socket << "Hello"
      puts "Hello"
      sleep 1
    end
  end
  # if Content-Type is text/html, html parser may delay rendering of text
  [200, { "Content-Encoding" => "chunked" }, body]
}