ID: 48434
User updated by: busia at tiscali dot it
Reported By: busia at tiscali dot it
Status: Bogus
Bug Type: Feature/Change Request
PHP Version: 5.3.0RC2
New Comment:
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
Previous Comments:
------------------------------------------------------------------------
[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;
}
}
------------------------------------------------------------------------
[2009-05-30 11:42:31] scott...@php.net
memory_get_usage(true) is the memory allocated from the system.
memory_get_usage() is the memory currently in use by PHP.
<?php
var_dump(memory_get_usage(), memory_get_usage(true));
$x = str_repeat('a', 4096);
var_dump(memory_get_usage(), memory_get_usage(true));
unset($x);
var_dump(memory_get_usage(), memory_get_usage(true));
Produces
int(332392) <-- Initial
int(524288) <-- system
int(336996) <-- After variable set
int(524288) <-- system
int(332916) <-- After variable unset
int(524288) <-- system
------------------------------------------------------------------------
[2009-05-30 10:08:12] busia at tiscali dot it
I know memory_get_usage() and memory_get_usage(true). But they don't
resolve the problem because the memory is not freed always when I unset
a variable than memory_get_usage can return the same before and after
creating a variable. See #48368. You said me that internal php memory is
different from system allocated memory, and I want to access internal
php memory. Memory_get_usage (with or without the first parameter) allow
only to access to syem allocated memory.
Please reply
------------------------------------------------------------------------
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the rest of the comments, please view the bug report online at
http://bugs.php.net/48434
--
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