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Bug #22055 Memory leak with references in objects
Submitted: 2003-02-04 14:35 UTC Modified: 2003-02-25 02:03 UTC
Votes:22
Avg. Score:4.8 ± 0.8
Reproduced:19 of 19 (100.0%)
Same Version:2 (10.5%)
Same OS:3 (15.8%)
From: jparneodo at yahoo dot fr Assigned:
Status: No Feedback Package: Scripting Engine problem
PHP Version: 4.3.1-dev OS: RedHat 7.2
Private report: No CVE-ID: None
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 [2003-02-04 14:35 UTC] jparneodo at yahoo dot fr
/*
If you don't set the UP property,
garbage collection is done in real time

If you set the UP property,
garbage collection is done on script shutdown only
and the VmSize increase.

This is a test case
but if a sub-object (in some package) creates a 
circular reference with a sub-sub-object you leak 
memory without the knowledge of it.
*/
for($i=1;$i<=$nb_loop;$i++){
	echo "<br>loop $i";
	flush();
	for($j=1;$j<=$nb_by_loop;$j++){
		$a=&new A(500);
		$a->b=&new B(500);
		$a->b->UP=&$a; // Memory Leak here
//		unset($a->b->up);
	}
	sleep($sleep_by_loop);
}

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 [2003-02-04 14:37 UTC] derick@php.net
oops!

you need to development snapshot from snaps.php.net, which should solve this.

Derick
 [2003-02-05 13:41 UTC] jparneodo at yahoo dot fr
Same result with PHP Version 4.3.1-dev
php4-STABLE-200302051830.tar.gz
Build Date  Feb 5 2003 20:08:24
 [2003-02-06 08:31 UTC] sniper@php.net
You were supposed to test this snapshot:

  http://snaps.php.net/php5-latest.tar.gz
 [2003-02-06 08:56 UTC] jparneodo at yahoo dot fr
You are asking me to test PHP 5,
but the bug is open for for PHP 4
 [2003-02-16 15:40 UTC] adey dot spam at bigfoot dot com
I am experiencing this problem with Win2k/IIS 5.0.

Memory usage increases until the server starts to page and crawl to a slow death.

I have helped this somewhat by writing an app to unload the ISAPI every half an hour, but it is still causing problems about once a week (on a very busy site).

Still preferable to using the CGI though....
 [2003-02-17 04:51 UTC] derick@php.net
Test with the php5 snapshot please:

  http://snaps.php.net/php5-latest.tar.gz

It won't be fixed in PHP 4 anyway as it has to do with the way objects work there.
 [2003-02-25 02:03 UTC] sniper@php.net
No feedback was provided. The bug is being suspended because
we assume that you are no longer experiencing the problem.
If this is not the case and you are able to provide the
information that was requested earlier, please do so and
change the status of the bug back to "Open". Thank you.


 [2004-02-23 11:21 UTC] tom at scl dot co dot uk
I had this problem with PHP4.3.3. I then found this bug report and upgraded to PHP5.0.0b4 to try and fix this problem and I still get the memory leak problem, there is some demo code below, you need to change /path/to/large/file. I've been using a file which is about 1.5mb and when PHP is set to stop when it reaches 8mb then it only makes it through the loop twice.

I'm 1.5 years into a project and I could really do with knowing if this is going to be fixed anytime soon so I can either wait for the fix or try and find a work around. Thanks for your time,
Tom

---

<?php
class C {
    var $ref;
    var $val;
 
    function C() {
        $this->val = file('/path/to/large/file');
    }
}
 
while (1) {
    $x = new C;
    $y = new C;
 
    $x->ref =& $y;
    $y->ref =& $x;
 
    unset($y);
    unset($x);
 
    echo ".";
}
?>
 [2004-03-01 05:07 UTC] tom at scl dot co dot uk
Is anyone looking into this?

I've found any method of releasing the objects fails, no just using the unset() function, if the object just go out of scope they aren't released, for ezample, if you do something like

function MyFunc() {
    $x = new C;
    $y = new C;
 
    $x->ref =& $y;
    $y->ref =& $x;
}

Then after the function has finished then the memory allocated for the local variables $x and $y is not freed up.
 [2005-06-17 16:25 UTC] apinstein at mac dot com
I have experienced this problem on PHP5 as well... here's a 
test script:


echo memory_get_usage() . " (initial)\n";
$t = new test;
echo memory_get_usage() . " (after: \$t = new test();)\n";
unset($t);
echo memory_get_usage() . " (after: unset(\$t);)\n";
echo "done\n";


class test
{
    protected $str;
    protected $t2;

    function __construct()
    {   
        print "construct test\n";
        $this->str = str_repeat('1234567890', 1000);
        $this->t2 = new test2($this);
    }

    function __destruct()
    {   
        print "destruct test\n";
    }
}
class test2
{
    protected $str;
    protected $t1;

    function __construct($t1)
    {   
        print "construct test2\n";
        $this->str = str_repeat('1234567890', 1000);
        $this->t1 = $t1;
    }

    function __destruct()
    {   
        print "destruct test2\n";
        unset($this->str);
    }
}


And the output of this script:

51416 (initial)
construct test
construct test2
72000 (after: $t = new test();)
72000 (after: unset($t);)
done
destruct test
destruct test2

It's definitely a real problem. Simply removing the cross-
referenced instance vars will remove the problem. However, 
as you can see, even explicitly calling unset() still 
doesn't release the objects or call destructors until the 
script EXITS. 

This is a *MAJOR* problem for anyone using OO to process 
large amounts of information.
 [2007-03-01 03:51 UTC] matthieu dot aubry at gmail dot com
I also have the same problem using 
PHP Version => 5.1.2
Build Date => Nov  2 2006 12:28:13
Server API => Command Line Interface

This bug is really annoying.

I'm working on a project which loads thousands of files parsed into objects. 
I use the technic
$this->myObjectMember->register($this);

which creates cross references. 

Calling unset() doesn't change anything, as seen in the examples provided above.

I would love to see this bug fixed! Thank you.
 [2009-04-01 13:45 UTC] phpuser at gmail dot com
Having the same issue with php 5.2.9.

As stated above, this is a major problem, as I'm using php to import/export data between databases, and I'm talking about millions rows.

I have to split the data to import, because even after using unset() the memory used by objects isn't released.

Please do something about this bug. It has been reported 6 years ago and is still here !!

Tested with php 5.2.6 and 5.2.9, both with linux and windows xp.
 [2009-04-02 23:32 UTC] medge at neverathome dot net
This problem still exists - this is causing us extreme headaches as we will need to have two object models in our system.

One which is useful, and one which is "in case we have to do anything with high load in PHP" and isn't an object model at all.

This seems like a pretty critical bug.
 [2009-04-14 16:21 UTC] web_Fell at hotmail dot com
We should close this as dupe of bug #33595:
http://bugs.php.net/bug.php?id=33595
 
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