# File lib/action_controller/session/mem_cache_store.rb, line 7
        def initialize(app, options = {})
          # Support old :expires option
          options[:expire_after] ||= options[:expires]

          super

          @default_options = {
            :namespace => 'rack:session',
            :memcache_server => 'localhost:11211'
          }.merge(@default_options)

          @pool = options[:cache] || MemCache.new(@default_options[:memcache_server], @default_options)
          unless @pool.servers.any? { |s| s.alive? }
            raise "#{self} unable to find server during initialization."
          end
          @mutex = Mutex.new

          super
        end