See PR: https://github.com/mongodb/mongoid/pull/5808

^^^

Currently there is a  Mongoid.disconnect_clients method but no Add Mongoid.reconnect_clients method. The documentation currently recommends this:

before_fork do |server, worker|
  Mongoid.disconnect_clients
end 

after_fork do |server, worker|
  Mongoid::Clients.clients.each do |name, client|
    client.close
    client.reconnect
  end
end

The after_fork should have a single Mongoid.reconnect_clients method instead of ad-hoc code.