Edit report at http://bugs.php.net/bug.php?id=53242&edit=1
ID: 53242
Comment by: ceo at l-i-e dot com
Reported by: einars at gmail dot com
Summary: count() slow for global / static arrays
Status: Bogus
Type: Bug
Package: Performance problem
Operating System: Arch Linux
PHP Version: 5.3.3
Block user comment: N
Private report: N
New Comment:
Call me crazy, but once you declare it global in the function, having a
local one seems kind of silly...
Why not just have the one zval?...
>From a guy who knows very little of php internals, but can't figure out
the purpose of a "local" $items when it's been declared global in the
function body.
And "static" should be its own zval, not interacting in any way shape or
form with any zval in any other scope... So it should have a refcount <
2 as well...
Previous Comments:
------------------------------------------------------------------------
[2010-11-05 02:40:02] cataphr...@php.net
To be expected.
When you do global $items; the underlying zval has its refcount
incremented to 2 since now it's referred to by the global symbol $items
and the local symbol $items and the is_ref flag is set.
Since sizeof does not receive its argument by reference and you're
giving it an is_ref zval, a separation is forced and the value if
copied. Since $items refers to a big variable (50k+ items), the
performance penalty is big.
To cut the story short: use $foo = $GLOBALS['items'].
------------------------------------------------------------------------
[2010-11-04 17:50:28] einars at gmail dot com
Description:
------------
When the arrays are defined global or static, the sizeof() / count
method suddenly gets very slow.
Test script:
---------------
<?php
$items = range(0, 50000);
$times = 200;
$time = microtime(true);
for ($i = 0; $i < $times; $i++) {
$foo = sizeof($items);
}
printf("Non-global access: %.2fs\n", microtime(true) - $time);
$time = microtime(true);
for ($i = 0; $i < $times; $i++) {
test_global();
}
printf("Global access: %.2fs\n", microtime(true) - $time);
function test_global() {
global $items;
$foo = sizeof($items);
}
Expected result:
----------------
% php array-test.php
Non-global access: 0.00s
Global access: 0.00s
Actual result:
--------------
% php array-test.php
Non-global access: 0.00s
Global access: 2.73s
------------------------------------------------------------------------
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Edit this bug report at http://bugs.php.net/bug.php?id=53242&edit=1
