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Message-ID: <28139bc05061000547cfc827d@mail.gmail.com>
Date: Fri, 10 Jun 2005 15:54:53 +0800
Reply-To: Xuefer <xuefer@gmail.com>
To: internals@lists.php.net
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Subject: strange php4.3.x foreach performance issue
From: xuefer@gmail.com (Xuefer)

"foreach ($arr as $k =3D> $v)" is 2 times as faster as "foreach ($arr as
$v)" in php4.3.x

both test under lastest cvs.

4.3.12-dev
testing with array[] =3D string
$v:     2.5590002536774
$k=3D>$v: 0.7020001411438
$v each():      1.025000333786
$k $v each():   1.1790001392365
testing with array[] =3D array(string)
$v:     0.50299978256226
$k=3D>$v: 0.70599985122681
$v each():      0.9909999370575
$k $v each():   1.172000169754

5.1.0-dev
testing with array[] =3D string
$v:     0.15599966049194
$k=3D>$v: 0.19999980926514
$v each():      0.78099966049194
$k $v each():   0.77299976348877
testing with array[] =3D array(string)
$v:     0.16900014877319
$k=3D>$v: 0.19900012016296
$v each():      0.71399998664856
$k $v each():   0.77100014686584


<?php
function mtime()
{
       list($s, $ms) =3D explode(' ', microtime());
       return $s + $ms;
}

function stopwatch()
{
       static $now;
       $old =3D $now;
       $now =3D mtime();
       return $now - $old;
}

function runtest($arr)
{
       $count =3D 1000;
       stopwatch();
       for ($i =3D 0; $i < $count; $i ++);
       $extra =3D stopwatch();

       stopwatch();
       for ($i =3D 0; $i < $count; $i ++) {
               $r =3D $arr;
               foreach ($r as $v) $dummy =3D $v;
       }
       echo '$v:', "\t", stopwatch() - $extra, "\n";

       stopwatch();
       for ($i =3D 0; $i < $count; $i ++) {
               $r =3D $arr;
               foreach ($r as $key =3D> $v) $dummy =3D $v;
       }
       echo '$k=3D>$v:', "\t", stopwatch() - $extra, "\n";

       stopwatch();
       for ($i =3D 0; $i < $count; $i ++) {
               $r =3D $arr;
               reset($r);
               while (list(, $v) =3D each($r)) $dummy =3D $v;
       }
       echo '$v each():', "\t", stopwatch() - $extra, "\n";

       stopwatch();
       for ($i =3D 0; $i < $count; $i ++) {
               $r =3D $arr;
               reset($r);
               while (list($k, $v) =3D each($r)) $dummy =3D $v;
       }
       echo '$k $v each():', "\t", stopwatch() - $extra, "\n";
}

echo PHP_VERSION, "\n";

echo "testing with array[] =3D string\n";
$arr =3D array();
for ($i =3D 0; $i < 100; $i ++) {
       $arr[] =3D str_repeat('-', 10240);
}
runtest($arr);

echo "testing with array[] =3D array(string)\n";
$arr =3D array();
for ($i =3D 0; $i < 100; $i ++) {
       $arr[] =3D array(str_repeat('-', 10240));
}
runtest($arr);
echo "testing with queryAll\n";

[quote: http://ez.no/community/blog/foreach_performance_improvement_backpor=
t]
This patch improves performance with foreach() where the key of the
array element is not interesting (for example foreach($array as
$value); ).
[/quote]