Bug #53416 [Opn->Bgs]: iterate over array of complex objects slower than array of simple objects
Edit report at http://bugs.php.net/bug.php?id=53416&edit=1
ID: 53416
Updated by: scottmac@php.net
Reported by: goetas at lignano dot it
Summary: iterate over array of complex objects slower than
array of simple objects
-Status: Open
+Status: Bogus
Type: Bug
Package: Performance problem
Operating System: Ubuntu Server 10
PHP Version: 5.3.3
Block user comment: N
Private report: N
New Comment:
foreach() copies the array to work on. Hence why a complex object takes
longer to
iterate as it takes longer to copy.
Previous Comments:
------------------------------------------------------------------------
[2010-11-26 14:44:50] goetas at lignano dot it
Description:
------------
I do not understand if is an error or not, but iterating over arrays
with complex objects is slower than iterate over arrays made with more
simple objects.
In some case (but i can't reproduce it), iterate over arrays with 100
elements is 100x slower than iterate other array made of 100 simpler
objects.
(sorry for my English)
Test script:
---------------
<?php
// create some arrays
// integer array (1000 items)
$vals = range(0,1000);
// simple object array (1000 items)
$obj = array_map(function($v){
$o = new stdClass();
$o->v = $v;
return $o;
}, $vals);
// more complex object array (1000 items)
$objs = array_map(function($v)use(&$obj){
$o = new stdClass();
$o->res = array();
for ($i = 0; $i<500; $i++){
$o->res[$i] = $obj[$i];
}
for (true; $i<1000; $i++){
$o->{'res'.$i} = $obj[$i];
}
return $o;
}, $vals);
// TESTS
// 1. loop over integer array
// 1000000 iterations
$t = microtime(1);
foreach ($vals as $o1){
foreach ($vals as $o2){
}
}
echo microtime(1)-$t."\n";
// 2. loop over simple object array
// 1000000 iterations
// 15% slower than loop n.1
$t = microtime(1);
foreach ($obj as $o1){
foreach ($obj as $o2){
}
}
echo microtime(1)-$t."\n";
// 3. loop over complex object array
// 1000000 iterations
// 50% slower than loop n.1
$t = microtime(1);
foreach ($objs as $o1){
foreach ($objs as $o2){
}
}
echo microtime(1)-$t."\n";
Expected result:
----------------
all loop should take the same amount of time. (at most with slight
differences)
Actual result:
--------------
loop n.3 is 50% slower than loop 1
loop n.3 is 30% slower than loop 2
in some case iterate over complex array can be 100x slower
------------------------------------------------------------------------
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Edit this bug report at http://bugs.php.net/bug.php?id=53416&edit=1
Thread (3 messages)