Edit report at http://bugs.php.net/bug.php?id=53416&edit=1
ID: 53416
User updated by: goetas at lignano dot it
Reported by: goetas at lignano dot it
Summary: iterate over array of complex objects slower than
array of simple objects
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:
That should be true for the first loop.
But in the second and third loop, the array $obj or $objs should be made
only of 1000 references of the real objects.
Iterating over the array of objects should copy only these references
and not the entire objects set.
So the loop n.2 and n.3 should require the same amount of time.
Previous Comments:
------------------------------------------------------------------------
[2010-11-27 04:12:47] [email protected]
foreach() copies the array to work on. Hence why a complex object takes
longer to
iterate as it takes longer to copy.
------------------------------------------------------------------------
[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
