PHP5 中 readfile() 函数的性能答案

【问题标题】：Performance of the readfile() function in PHP5PHP5 中 readfile() 函数的性能
【发布时间】：2014-11-04 18:26:31
【问题描述】：

我在浏览器中开始下载的速度延迟（不是下载速度，而是点击下载链接和下载出现在浏览器中之间的时间）时遇到了一些问题。

我已经尽可能地简化了我的代码；

$filepath = $this->_resourceFile;
ob_start(); 
$start = microtime(true);
readfile($filepath);
$end = microtime(true) - $start; 
Mage::log('Time taken to serve file was '.$end);

（您会看到这是 Magento 的一部分，我对 Magento 提供可下载产品文件的方式进行了大量编辑，以尝试加快速度。这在大多数情况下都有效，但我仍然遇到问题)

我放置的日志如下所示；

2014-10-23T14:19:15+00:00 DEBUG (7): Time taken to serve file was 0.067724943161011
2014-10-23T14:24:48+00:00 DEBUG (7): Time taken to serve file was 0.069678068161011
2014-10-23T14:25:58+00:00 DEBUG (7): Time taken to serve file was 0.080054998397827
2014-10-23T14:26:28+00:00 DEBUG (7): Time taken to serve file was 0.067059993743896
2014-10-23T14:27:27+00:00 DEBUG (7): Time taken to serve file was 0.068262100219727
2014-10-23T14:30:08+00:00 DEBUG (7): Time taken to serve file was 0.066760063171387
2014-10-23T14:36:34+00:00 DEBUG (7): Time taken to serve file was 90.616213083267
2014-10-23T14:45:11+00:00 DEBUG (7): Time taken to serve file was 0.065201997756958
2014-10-23T14:45:22+00:00 DEBUG (7): Time taken to serve file was 0.073112010955811
2014-10-23T14:46:56+00:00 DEBUG (7): Time taken to serve file was 87.481207132339
2014-10-23T14:47:44+00:00 DEBUG (7): Time taken to serve file was 36.195640087128
2014-10-23T14:47:48+00:00 DEBUG (7): Time taken to serve file was 0.067437887191772
2014-10-23T14:48:01+00:00 DEBUG (7): Time taken to serve file was 0.068021059036255
2014-10-23T14:48:06+00:00 DEBUG (7): Time taken to serve file was 0.028129100799561
2014-10-23T14:48:13+00:00 DEBUG (7): Time taken to serve file was 0.067390918731689
2014-10-23T14:49:00+00:00 DEBUG (7): Time taken to serve file was 0.065808057785034
2014-10-23T14:49:06+00:00 DEBUG (7): Time taken to serve file was 0.06847882270813
2014-10-23T14:49:48+00:00 DEBUG (7): Time taken to serve file was 0.063234090805054
2014-10-23T14:50:03+00:00 DEBUG (7): Time taken to serve file was 0.059723138809204
2014-10-23T14:50:08+00:00 DEBUG (7): Time taken to serve file was 0.068203926086426
2014-10-23T14:50:13+00:00 DEBUG (7): Time taken to serve file was 0.065500974655151
2014-10-23T14:50:16+00:00 DEBUG (7): Time taken to serve file was 0.064054012298584
2014-10-23T14:50:20+00:00 DEBUG (7): Time taken to serve file was 0.068597078323364
2014-10-23T14:50:24+00:00 DEBUG (7): Time taken to serve file was 0.026658058166504
2014-10-23T14:51:47+00:00 DEBUG (7): Time taken to serve file was 0.065510988235474
2014-10-23T14:51:56+00:00 DEBUG (7): Time taken to serve file was 0.06929087638855
2014-10-23T14:52:00+00:00 DEBUG (7): Time taken to serve file was 0.026684999465942
2014-10-23T14:52:32+00:00 DEBUG (7): Time taken to serve file was 0.067147016525269
2014-10-23T14:55:55+00:00 DEBUG (7): Time taken to serve file was 0.067998886108398

您会看到，在 0.06... 中，有 90 秒等待、87 秒等待和 36 秒等待。什么可能导致这些峰值？

该站点在 Linux 服务器上运行，使用 apache 和 nginx，使用 PHP5.3.3。会不会是服务器负载问题？我是否认为用户带宽应该与这种延迟几乎无关？

【问题讨论】：

耗时较长的文件有什么不同吗？类型、大小等
如果您在 Apache 中使用 PHP，请阅读 X-Sendfile。如果你在 Nginx 中使用 PHP，那么 X-Accel-Redirect.
@Jim - 不是真的，虽然它们不是同一个文件（大约 3 个的混合文件），但上面的所有日志都是使用大小约为 90mb 的 MP3 创建的。
我无法使用 X-SendFile 或 X-Accel-Redirect，因为我正在为我的文件设置自定义标头，似乎在几次下载后，文件在一定数量的时间内始终保持快速时间，几乎就像它被缓存一样。有人有什么建议吗？

标签： php apache magento nginx readfile

【解决方案1】：

所以，经过大量调查，这似乎是服务器问题。

服务器在第一次访问时将文件存储在RAM中，以加快将来的访问速度。将文件复制到 RAM 所花费的时间导致了延迟 - 一旦文件在 RAM 中，它就会立即被提供。

我们更改了服务器上的 IO 资源设置，初始下载时间现在降至 6 秒，而不是 90 秒。

【讨论】：