有什么keep-alive特点？我该如何启用它？
以下是 chrome 的 Page Speed 插件的输出。
启用 Keep-Alive 主机 {MYWEBSITE.COM} 应该启用 Keep-Alive。它提供以下资源。
http://MYWEBSITE.com/
http://MYWEBSITE.com/fonts/AGENCYR.TTF
http://MYWEBSITE.com/images/big_mini/0002_mini.jpeg
http://MYWEBSITE.com/images/big_mini/0003_mini.jpeg
http://MYWEBSITE.com/images/big_mini/0004_mini.jpeg
http://MYWEBSITE.com/images/big_mini/0005_mini.jpeg
http://MYWEBSITE.com/images/big_mini/0006_mini.jpeg
http://MYWEBSITE.com/images/big_mini/0007_mini.jpeg
http://MYWEBSITE.com/images/.jpeg
http://MYWEBSITE.com/images/small/0002S.jpeg
http://MYWEBSITE.com/images/small/0003S.jpeg
http://MYWEBSITE.com/images/small/0004S.jpeg
http://MYWEBSITE.com/images/small/0005S.jpeg
http://MYWEBSITE.com/images/small/0006S.jpeg
http://MYWEBSITE.com/images/small/0007S.jpeg
http://MYWEBSITE.com/images/small/0008S.jpeg
http://MYWEBSITE.com/images/small/0009S.jpeg
http://MYWEBSITE.com/images/small/0010S.jpeg
http://MYWEBSITE.com/images/small/0011S.jpeg
http://MYWEBSITE.com/images/small/0012S.jpg
http://MYWEBSITE.com/images/small/0013S.jpeg
http://MYWEBSITE.com/images/small/0014S.jpeg
http://MYWEBSITE.com/images/small/0015S.jpeg
http://MYWEBSITE.com/images/small/0016S.jpeg
http://MYWEBSITE.com/images/small/0017S.jpeg
http://MYWEBSITE.com/images/small/0018S.jpeg
http://MYWEBSITE.com/images/small/0019S.jpeg
http://MYWEBSITE.com/yoxview/yoxview.css
http://MYWEBSITE.com/yoxview/images/empty.gif
http://MYWEBSITE.com/yoxview/images/left.png
http://MYWEBSITE.com/yoxview/images/popup_ajax_loader.gif
http://MYWEBSITE.com/yoxview/images/right.png
http://MYWEBSITE.com/yoxview/images/sprites.png
http://MYWEBSITE.com/yoxview/img3_mini.jpeg
http://MYWEBSITE.com/yoxview/jquery.yoxview-2.21.min.js
http://MYWEBSITE.com/yoxview/lang/en.js
http://MYWEBSITE.com/yoxview/yoxview-init.js