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:
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.
Previous Comments:
------------------------------------------------------------------------
[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.
------------------------------------------------------------------------
[2009-05-30 13:00:52] busia at tiscali dot it
I unsderstand what you say but my request is different: when I posted
bug #48368, j...@php.net answered me:
------------------------
unset != free. The memory is freed once the process shuts down. Until
that, it's available inside the process. This is not a leak.
------------------------
I need a function that tell me the amount of this memory "available
inside the process" or even better the difference between
memory_get_usage() and this memory "available inside the process".
I don't think this is bogus, i think this must be an "open" feature
request.
Thanks
------------------------------------------------------------------------
[2009-05-30 12:23:24] lbarn...@php.net
scott you are right, however it seems the behavior differs a bit when
unset()ing small-enough variables.
memory_get_usage(false) does not takes into account the "small blocks
cache" used by the allocator (not the same as the malloc()ed blocks
cache).
This causes the reported memory usage to not always decrease when
unset()ing a variable:
<?php
$foo = "bar";
var_dump(memory_get_usage());
var_dump(memory_get_usage());
unset($foo);
var_dump(memory_get_usage());
?>
int(91448) <-- first call
int(91696) <-- before unset
int(91696) <-- after unset (== before unset)
This patch may fix this:
Index: Zend/zend_alloc.c
===================================================================
RCS file: /repository/ZendEngine2/zend_alloc.c,v
retrieving revision 1.144.2.3.2.43.2.23
diff -u -p -r1.144.2.3.2.43.2.23 zend_alloc.c
--- Zend/zend_alloc.c 1 Apr 2009 16:55:47 -0000 1.144.2.3.2.43.2.23
+++ Zend/zend_alloc.c 30 May 2009 12:12:48 -0000
@@ -2496,7 +2496,11 @@ ZEND_API size_t zend_memory_usage(int re
if (real_usage) {
return AG(mm_heap)->real_size;
} else {
- return AG(mm_heap)->size;
+ size_t usage = AG(mm_heap)->size;
+#if ZEND_MM_CACHE
+ usage -= AG(mm_heap)->cached;
+#endif
+ return usage;
}
}
------------------------------------------------------------------------
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http://bugs.php.net/48434
--
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