I am having a php file which parses the meta tags out of the html report files and display them in a table. Until now it has wroked fine on PHP 5.2.4.4, now after installing the version 5.3.5, the page doesn't load and give an error:

"PHP Fatal error:  Out of memory (allocated xxxxxx) (tried to allocate xxxxxx
01 bytes) in File on line xx.". I start increasing the memory allocation in php.ini almost upto 1000MB, but still the same error.

If i downgrade to PHP 5.2.4.4, its working again. What could the problem be?

For some reason, the Test Script given here, gives the same error message on version PHP 5.3.5, 5.2.4.4, 4.

I can confirm the issue affects PHP 5.3.3 on Windows 2008 and 5.3.5 on Windows 7.

I have tested on Ubuntu with 5.3.2 and 5.3.5 and the bug is not present and the script works.

Please try with 5.3.8

In version 5.3.8 error still occurs

E:\SVN>test.php
5.3.8
Limit:4024M
100
1000
PHP Fatal error:  Out of memory (allocated 736362496) (tried to allocate 734003
01 bytes) in E:\SVN\test.php on line 25

---
echo phpversion()."\n"; 

 ini_set ('memory_limit', '4024M');
 echo 'Limit:'.ini_get ('memory_limit')."\n";

$mb='';
$x=0;
do {
$x++;
$mb.='X';
}while ($x< 1048576);
echo "100\n";
$x=0;
$mb100='';
do {
$x++;
$mb100.=$mb;
}while ($x< 100);
echo "1000\n";
$x=0;
$gb='';
do {
$x++;
$gb.=$mb100;
}while ($x< 10);
echo "OK\n";



Fatal error: Out of memory (allocated 736362496) (tried to allocate 734003201 b
tes) in E:\SVN\test.php on line 25
zend_mm_heap corrupted

Fatal error: Out of memory (allocated 537919488) (tried to allocate 536870913 
bytes) XXXX
zend_mm_heap corrupted

The error occurs regardless of the setting memory_limit

The error still occurs

Still an issue on PHP 5.3.10 tested on Windows 2008 and Windows 7 using FCGI and mod_php on both platforms.

This is caused by heap size limitation of Windows. A process can use
heap up to nealy 1500MB on recent versions of Windows.

Because of fragmentation, actual limit is less than 1500MB.
For example, I added some debugging code to PHP (see
https://gist.github.com/4011991 ) and ran following sample
script.

----

<?php
ini_set('memory_limit', '3072M');
define('MB', 1024 * 1024);
$str = str_repeat('a', 400 * MB);
$str = '' . $str;
$str .= $str;

>php bug53980.php
[alloc]        segment: 0x02CF0048-0x02D30047 size: 262144 (0MB)
[free]         segment: 0x02CF0048
[alloc]        segment: 0x02CF0048-0x02D30047 size: 262144 (0MB)
[alloc]        segment: 0x02D30050-0x02D7004F size: 262144 (0MB)
[alloc]        segment: 0x102A0020-0x292E001F size: 419692544 (400MB)
[alloc]        segment: 0x292F0020-0x4233001F size: 419692544 (400MB)
[free]         segment: 0x102A0020
[realloc from] segment: 0x292F0020
[realloc to]   segment: 0x00000000-0x3203FFFF size: 839122944 (800MB)

Fatal error: Out of memory (allocated 420216832) (tried to allocate 838860801 
bytes) in C:\***\bug55980.php on line 6
zend_mm_heap corrupted

----

Dispite the heap has nearly 1100MB free space in total, there is no
contiguous 800MB space. Then HeapRealloc() fails and returns NULL.

Prior to PHP 7.0.0, official non-experimental PHP builds for
Windows were only available for x86 which is 32bit even on 64bit
Windows versions, where the address space of a single process is
limited to at most 2GB (or 3GB with 4GT), and in practice, heap
space is way more limited.  As of PHP 7.0.0, official
non-experimental x64 PHP builds for Windows are available; use
these!