在Apache中使用mod_rewrite

Question

I have image hosting. All image requests redirect to a PHP script with mod_rewrite. PHP script uses function fread() and displays picture from another file. I want to know, does this use a lot of processor time or not?

Answer 1

It depends on how much you think "a lot of processor time" is, but from what you're describing, the processing time required by mod_rewrite and PHP is trivial compared to the I/O time to read the image from disk and send it over the network.

If you're concerned about speed, caching the images in memory will probably have the most benefit.

Answer 2

Yes, this is putting considerable strain on the web server, because the PHP interpreter has to be initialized for every small resource request, and passes through the data. The consensus is that this is not a good thing to do on a high-traffic website.

Why are you doing this, are you resizing images?

Answer 3

在达到CPU限制之前，您将用完内存：-)读/写文件不是CPU密集型任务，但是为此创建的每个apache进程最多会占用50 MB的RAM。

Answer 4

If you want to send images fast and secure, you should look into X-SendFile - this allows your php scripts to tell your Webserver to send files not directly accessible by url using something like header('X-SendFile: /path/to/the/file');

For apache there is mod_xsendfile ( http://tn123.ath.cx/mod_xsendfile/ ) though labeled beta, it has proven to be very stable in production, and the its sourcecode is rather small and can be audited easily.