为什么 require_once 不好用? [英] Why is require_once so bad to use?
问题描述
我读到的关于更好的 PHP 编码实践的所有内容都在说不要使用 require_once
因为速度.
Everything I read about better PHP coding practices keeps saying don't use require_once
because of speed.
这是为什么?
做与 require_once
相同的事情的正确/更好的方法是什么?如果重要的话,我正在使用 PHP 5.
What is the proper/better way to do the same thing as require_once
? If it matters, I'm using PHP 5.
推荐答案
require_once
和 include_once
都要求系统记录已包含/需要的内容.每个 *_once
调用都意味着检查该日志.所以肯定有一些额外的工作要做,但足以损害整个应用程序的速度?
require_once
and include_once
both require that the system keeps a log of what's already been included/required. Every *_once
call means checking that log. So there's definitely some extra work being done there but enough to detriment the speed of the whole app?
...我真的很怀疑...除非您使用真的旧硬件或很多.
... I really doubt it... Not unless you're on really old hardware or doing it a lot.
如果您正在做数千个*_once
,那么您可以以更轻松的方式自己完成这项工作.对于简单的应用程序,只需确保只包含一次应该就足够了,但是如果您仍然遇到重新定义错误,您可以这样做:
If you are doing thousands of *_once
, you could do the work yourself in a lighter fashion. For simple apps, just making sure you've only included it once should suffice but if you're still getting redefine errors, you could something like this:
if (!defined('MyIncludeName')) {
require('MyIncludeName');
define('MyIncludeName', 1);
}
我个人会坚持使用 *_once
语句,但在愚蠢的百万遍基准测试中,您可以看到两者之间的区别:
I'll personally stick with the *_once
statements but on silly million-pass benchmark, you can see a difference between the two:
php hhvm
if defined 0.18587779998779 0.046600103378296
require_once 1.2219581604004 3.2908599376678
require_once
慢 10-100 倍,奇怪的是 require_once
在 hhvm
中似乎更慢.同样,如果您运行 *_once
数千次,这仅与您的代码相关.
10-100× slower with require_once
and it's curious that require_once
is seemingly slower in hhvm
. Again, this is only relevant to your code if you're running *_once
thousands of times.
<?php // test.php
$LIMIT = 1000000;
$start = microtime(true);
for ($i=0; $i<$LIMIT; $i++)
if (!defined('include.php')) {
require('include.php');
define('include.php', 1);
}
$mid = microtime(true);
for ($i=0; $i<$LIMIT; $i++)
require_once('include.php');
$end = microtime(true);
printf("if defined %s
require_once %s
", $mid-$start, $end-$mid);
<小时>
<?php // include.php
// do nothing.
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