Manage ActiveRecord connection pool with rack handler

active_record.rb

#This is a Rack middle to release the connections checkout from the connection pool
#in a rack multithreaded environment
# This is mandatory outside of ActionController, as ActiveRecord request you to handle the 
# release of the connections into the pool. If you don't do it, every n thread (where n is 
# the AR connection pool size) will be stucked waiting for a 5s AR empty pool timeout
module Rack
  module ActiveRecord
    def initialize(app)
      @app = app
    end
      
    def call(env)
      response = @app.call(env)
    ensure
      ActiveRecord::Base.clear_active_connections!
      response
     end
  end
end