# File lib/rack/session/memcache.rb, line 28
      def initialize(app, options={})
        super

        @mutex = Mutex.new
        mserv = @default_options[:memcache_server]
        mopts = @default_options.
          reject{|k,v| MemCache::DEFAULT_OPTIONS.include? k }
        @pool = MemCache.new mserv, mopts
        unless @pool.active? and @pool.servers.any?{|c| c.alive? }
          raise 'No memcache servers'
        end
      end