Question

Everything I read about better PHP coding practices keeps saying don’t use require_once because of speed.

Why is this?

What is the proper/better way to do the same thing as require_once? If it matters, I’m using PHP 5.

Answer 1

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?

… I really doubt it… Not unless you’re on really old hardware or doing it a lot.

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); } 

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 

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.

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<?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\t%s\nrequire_once\t%s\n', $mid-$start, $end-$mid); 

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<?php // include.php  // do nothing.