Gemfile

gem 'raindrops'

unicorn.rb

before_fork do |server, worker|
  require 'raindrops'

  Thread.new do
    begin
      socket = "0.0.0.0:#{ENV['PORT']}"
      stats = Raindrops::Linux.tcp_listener_stats([socket])[socket]
      STDOUT.sync = true
      puts "raindrops socket=#{socket} active=#{stats.active} queued=#{stats.queued}\n"
    end while sleep(1)
  end if defined?(Raindrops::Linux) and ENV['RAINDROPS_STATS_ENABLED']
  ...
end