# File lib/sidekiq/limit_fetch/global/selector.rb, line 15
    def uuid
      # - if we'll remove "@uuid ||=" from inside of mutex
      # then @uuid can be overwritten
      # - if we'll remove "@uuid ||=" from outside of mutex
      # then each read will lead to mutex
      @uuid ||= MUTEX_FOR_UUID.synchronize { @uuid || SecureRandom.uuid }
    end