检查每个请求的javascript / css文件修改时间

Question

We have two files in header of every web page - a ccs and a javascript file:

<script type="text/javascript" src="/js/scripts.js?1234"></script>
<link href="styles.css?2345" rel="stylesheet" type="text/css" />

Every time we modify a css/javascript file we increase the ?1234 parameter in the end of filename. Recently a member of the team proposed to replace this manual updating (that we have sometimes forgot to do) with PHP code that checks the file modification time itself:

<script type="text/javascript" src="/js/scripts.js?<?php echo filemtime('/js/scripts.js');?>"/>
<link href="styles.css?<?php echo filemtime('styles.css');?>" rel="stylesheet" type="text/css" />

The question is that how much slower (if at all) it makes the requests? Should we do it? We run our system in Linux server on Amazon EC2.

Answer 1

Filetime is slow but using it 2 times in a webpage maybe ok. But I would cache the result and only update it sometime (with a conjob for example).

Well if you are checking 1000 files, filemtime will actually DOUBLE the amount of time used if just reading the file with file_get_contents!

-> http://ckon.wordpress.com/2008/09/16/filemtime-the-performance-killer/