我有大量的PHP对象用于神经网络,我必须迭代这些对象并在上面执行一些数学运算。我在想,在类的实例上使用关联数组会不会更好?
我正在处理围绕3640
对象和围绕500
时间的迭代(充其量),所以任何微优化都会有很大帮助。做$object['value']
必然比做$object->value
快吗?
编辑:,因此它们都是相同的。但我猜构造函数会有一些开销?无论哪种方式,我都不想用我漂亮的类来换取脏的数组:P
发布于 2014-06-03 01:03:23
基于Quazzle的代码,我运行了下一段代码(5.4.16 windows 64位):
<?php
class SomeClass {
public $aaa;
public $bbb;
public $ccc;
}
function p($i) {
echo '<pre>';
print_r($i);
echo '</pre>';
}
$t0 = microtime(true);
$arraysOf=array();
$inicio=memory_get_usage();
for ($i=0; $i<1000; $i++) {
$z = array();
for ($j=0; $j<1000; $j++) {
$z['aaa'] = 'aaa';
$z['bbb'] = 'bbb';
$z['ccc'] = $z['aaa'].$z['bbb'];
}
$arraysOf[]=$z;
}
$fin=memory_get_usage();
echo '<p>arrays: '.(microtime(true) - $t0)."</p>";
echo '<p>memory: '.($fin-$inicio)."</p>";
p($z);
$t0 = microtime(true);
$arraysOf=array();
$inicio=memory_get_usage();
for ($i=0; $i<1000; $i++) {
$z = new SomeClass();
for ($j=0; $j<1000; $j++) {
$z->aaa = 'aaa';
$z->bbb = 'bbb';
$z->ccc = $z->aaa.$z->bbb;
}
$arraysOf[]=$z;
}
$fin=memory_get_usage();
echo '<p>arrays: '.(microtime(true) - $t0)."</p>";
echo '<p>memory: '.($fin-$inicio)."</p>";
p($z);
$t0 = microtime(true);
$arraysOf=array();
$inicio=memory_get_usage();
for ($i=0; $i<1000; $i++) {
$z = new stdClass();
for ($j=0; $j<1000; $j++) {
$z->aaa = 'aaa';
$z->bbb = 'bbb';
$z->ccc = $z->aaa.$z->bbb;
}
$arraysOf[]=$z;
}
$fin=memory_get_usage();
echo '<p>arrays: '.(microtime(true) - $t0)."</p>";
echo '<p>memory: '.($fin-$inicio)."</p>";
p($z);
?>
我得到了下一个结果:
arrays: 1.8451430797577
memory: 460416
Array
(
[aaa] => aaa
[bbb] => bbb
[ccc] => aaabbb
)
arrays: 1.8294548988342
memory: 275696
SomeClass Object
(
[aaa] => aaa
[bbb] => bbb
[ccc] => aaabbb
)
arrays: 2.2577090263367
memory: 483648
stdClass Object
(
[aaa] => aaa
[bbb] => bbb
[ccc] => aaabbb
)
php 5.4的结论
marginally).
ps:需要注意的是,如果定义了类,但是定义了成员,那么这个类的使用就会变慢。它还使用了更多的内存。显然秘诀在于定义成员
更新
我从php 5.4更新到php 5.5 (5.5.12 x86 windows)。
arrays: 1.6465699672699
memory: 460400
Array
(
[aaa] => aaa
[bbb] => bbb
[ccc] => aaabbb
)
arrays: 1.8687851428986
memory: 363704
SplFixedArray Object
(
[0] => aaa
[1] => bbb
[2] => aaabbb
)
arrays: 1.8554251194
memory: 275568
SomeClass Object
(
[aaa] => aaa
[bbb] => bbb
[ccc] => aaabbb
)
arrays: 2.0101680755615
memory: 483656
stdClass Object
(
[aaa] => aaa
[bbb] => bbb
[ccc] => aaabbb
)
php 5.5的结论
发布于 2012-12-08 22:14:42
我使用以下代码进行“性能分析”(1,000个实例,1000.000次读/写):
function p($i) {
echo '<pre>';
print_r($i);
echo '</pre>';
}
$t0 = microtime(true);
for ($i=0; $i<1000; $i++) {
$z = array();
for ($j=0; $j<1000; $j++) {
$z['aaa'] = 'aaa';
$z['bbb'] = 'bbb';
$z['ccc'] = $z['aaa'].$z['bbb'];
}
}
echo '<p>arrays: '.(microtime(true) - $t0);
p($z);
$t0 = microtime(true);
for ($i=0; $i<1000; $i++) {
$z = (object) null;
for ($j=0; $j<1000; $j++) {
$z->aaa = 'aaa';
$z->bbb = 'bbb';
$z->ccc = $z->aaa.$z->bbb;
}
}
echo '<p>obj: '.(microtime(true) - $t0);
p($z);
echo '<p> phpversion '.phpversion();
它在我的LINUX中输出以下内容:
arrays: 1.1085488796234
Array
(
[aaa] => aaa
[bbb] => bbb
[ccc] => aaabbb
)
obj: 1.2824709415436
stdClass Object
(
[aaa] => aaa
[bbb] => bbb
[ccc] => aaabbb
)
phpversion 5.2.17
因此,结论是:即使在PHP5.2上,对象也很慢。除非你真的需要对象的oop特性,否则不要使用对象。
发布于 2019-06-05 22:29:31
脚本@ PHP 7.3.5
SomeClass Object
是最快的,lightest.Array
是1.32倍的速度。2.70x memory.stdClass Object
1.65x速度。2.94x内存。原始输出:
arrays: 0.064794063568115
memory: 444920
Array (
[aaa] => aaa
[bbb] => bbb
[ccc] => aaabbb
)
arrays: 0.048975944519043
memory: 164512
SomeClass Object (
[aaa] => aaa
[bbb] => bbb
[ccc] => aaabbb
)
arrays: 0.081161022186279
memory: 484416
stdClass Object (
[aaa] => aaa
[bbb] => bbb
[ccc] => aaabbb
)
https://stackoverflow.com/questions/2193049
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