require 'mysql2/em'

i = 100_000
connections = 0

EM.run do
  (looop = proc{

    if connections < 4
      connections += 1

      client = Mysql2::EM::Client.new
      defer = client.query "SELECT 1 as first_query"

      defer.callback do |result|
        i -= 1
        connections -= 1
        client.close
      end
    end

   EM.next_tick(looop)
  }).call


  puts i if ( i % 100 ) == 0

  EM.stop if i == 0
end