Using Redis will allow ab_users to persist across sessions or machines.

[Midhat Salahov]

I do as the documentation

Split.configure do |config|
  config.persistence = Split::Persistence::RedisAdapter.with_config(:lookup_by => proc { |context| context.current_user_id }
end

and get an error:

undefined method `current_user_id' for #<#<Class:0x007fb95fc34248>:0x007fb95fdfc288>
Please, help and sorry for my english :)