PHP :: Bug #77209 :: Leaks memory

[2018-11-27 12:09 UTC] silicid at gmail dot com

Description:
------------
You must create a file with the specified code.
If you execute method "is_object" from "$this" and unset the object, then leaks memory. But if you call method "is_object" for "$object", then there are no problems.
In version 7.1 there are no problems. There are no problems in Windows.


Test script:
---------------
<?php
class Test {
    public function __construct() {
        for ($i = 0; $i < 1000; ++$i) {
            $this->result[] = rand(1, 1000);
        }
    }
    function object() {
        is_object($this);
    }
}

$memory = memory_get_usage();
for ($i = 0; $i < 1; ++$i) {
    $object = new Test();
    $object->object();
    unset($object);
}
var_dump(memory_get_usage() - $memory);

$memory = memory_get_usage();
for ($i = 0; $i < 100; ++$i) {
    $object = new Test();
    $object->object();
    unset($object);
}
var_dump(memory_get_usage() - $memory);

$memory = memory_get_usage();
for ($i = 0; $i < 100; ++$i) {
    $object = new Test();
    is_object($object);
    unset($object);
}
var_dump(memory_get_usage() - $memory);


Expected result:
----------------
int(0)
int(0)
int(0)


Actual result:
--------------
int(37336)
int(3733600)
int(0)

[2018-11-27 13:20 UTC] silicid at gmailc dot om

PHP Version 7.2.12-1+0~20181112102353.11+jessie~1.gbp55f215
System 	Linux VV10015-z2174 4.15.17-3-pve #1 SMP PVE 4.15.17-13 (Mon, 18 Jun 2018 17:15:04 +0200) x86_64 
Build Date 	Nov 12 2018 13:46:27

[2018-11-27 13:39 UTC] danack@php.net

-Status: Open +Status: Feedback

[2018-11-27 13:39 UTC] danack@php.net

please could you check again, with code like the below as I don't think the garbage collection kicks in immediately every single time, and also if it is actually a memory leak, the memory usage should continue to go up, rather than just be slightly higher for a moment. 

The output of the script below for me is:

int(0)
int(0)
int(32)
int(0)
int(0)
int(32)
int(0)
int(0)
int(32)...

https://3v4l.org/dPZ2R


class Test {
    public function __construct() {
        for ($i = 0; $i < 1000; ++$i) {
            $this->result[] = rand(1, 1000);
        }
    }
    function object() {
        is_object($this);
    }
}




function checkMemory($memoryAtStart)
{
    for ($i = 0; $i < 1; ++$i) {
        $object = new Test();
        $object->object();
        unset($object);
    }
    var_dump(memory_get_usage() - $memoryAtStart);

    $memoryAtStart = memory_get_usage();
    for ($i = 0; $i < 100; ++$i) {
        $object = new Test();
        $object->object();
        unset($object);
    }
    var_dump(memory_get_usage() - $memoryAtStart);

    $memoryAtStart = memory_get_usage();
    for ($i = 0; $i < 100; ++$i) {
        $object = new Test();
        is_object($object);
        unset($object);
    }
    var_dump(memory_get_usage() - $memoryAtStart);
}

$memoryAtStart = null;

for ($x=0; $x<100; $x++) {
    if ($memoryAtStart === null) {
        $memoryAtStart = memory_get_usage();
    }

    checkMemory($memoryAtStart);
    gc_collect_cycles();
}

[2018-11-27 14:05 UTC] silicid at gmailc dot om

It depends on the number of objects created.
The output for me is:

int(37336)
int(3733600)
int(0)
int(3808384)
int(3733600)
int(0)
int(7579320)
int(3733600)
int(0)
int(11350256)
int(3733600)
int(0)
int(15121192)
int(3733600)
int(0)
int(18892128)
int(3733600)
int(0)
int(22663064)
int(3733600)
int(0)
int(26434000)
int(3733600)
int(0)
int(30204936)
int(3733600)
int(0)
int(33975872)
int(3733600)
int(0)...

[2018-12-09 04:22 UTC] php-bugs at lists dot php dot 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 "Re-Opened". Thank you.

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