ID: 48434
User updated by: busia at tiscali dot it
Reported By: busia at tiscali dot it
-Status: Closed
+Status: Open
Bug Type: *General Issues
PHP Version: 5.3.0RC2
New Comment:
But this cache would be used When I create $foo the dimensione grows
from 33847560 to 33847640 (80 bytes extra). This didn't happen using
php3.0rc2 but happens using last snapshot
Previous Comments:
------------------------------------------------------------------------
[2009-05-31 09:10:46] lbarn...@php.net
PHP uses an array internally to store all objects. When you create more
objects, the array is grown. When you destroy some objects, the array is
not resized, so that creating other objects is faster.
This is the difference you see; ~32 bytes per object.
This is not due to the allocator. There is a few other caches of this
kind in PHP that make it running faster.
------------------------------------------------------------------------
[2009-05-31 07:44:54] busia at tiscali dot it
The correction create an other problem: look this script:
<?
ini_set('memory_limit','300M');
class a {
}
echo memory_get_usage()."\n";
$a=array();
for ($i=0; $i<=1000000; $i++) {
$a[]= new a();
}
echo memory_get_usage()."\n";
unset($a);
echo memory_get_usage()."\n";
$b=10000;
echo memory_get_usage()."\n";
?>
Regarding this code in bug #48368 you said me that unset != free. The
memory can remain occupied also after I unset an array, that memory is
reused when I set a new variable.
Now it is is possibile to check $foo dimension but the memory is not
reused. The output of the script is:
325792
230042232
33847560
33847640
It seems that the memory between 325792 and 33847560 is lost, it is not
reused when I set $foo.
------------------------------------------------------------------------
[2009-05-30 16:44:58] lbarn...@php.net
This bug has been fixed in CVS.
Snapshots of the sources are packaged every three hours; this change
will be in the next snapshot. You can grab the snapshot at
http://snaps.php.net/.
Thank you for the report, and for helping us make PHP better.
------------------------------------------------------------------------
[2009-05-30 14:35:56] busia at tiscali dot it
Look this code:
----------------
<?
ini_set('memory_limit','300M');
class a {
}
echo "a - ".(memory_get_usage(true) - memory_get_usage())."\n";
$a=array();
for ($i=0; $i<=1000000; $i++) {
$a[]= new a();
}
echo "b - ".(memory_get_usage(true) - memory_get_usage())."\n";
unset($a);
echo "c - ".(memory_get_usage(true) - memory_get_usage())."\n";
$foo=10000;
echo "d - ".(memory_get_usage(true) - memory_get_usage())."\n";
?>
-------------
That show
a - 201640
b - 774800
c - 685360
d - 685360
------------------------
If it is as you said the output near "d" should be different from the
output near "c" but they are identical. I want to know how many internal
mamory is used from the "$foo" variable. I know the the system memory is
the same because php don't make always garbage collection but it collect
on the request end bue i want to be able to know how much memory is
interested by section of code. Using your code seems that $foo is
registered on the void.
Thanks
------------------------------------------------------------------------
[2009-05-30 13:29:54] scott...@php.net
What aren't you understanding?
memory_get_usage(true) = memory allocated to process from system
memory_get_usage() = memory actually in use for PHP
Therefore
memory_get_usage(true) - memory_get_usage()
That's the memory that has been allocated from the system but isn't
used for variables yet.
------------------------------------------------------------------------
The remainder of the comments for this report are too long. To view
the rest of the comments, please view the bug report online at
http://bugs.php.net/48434
--
Edit this bug report at http://bugs.php.net/?id=48434&edit=1
