Thank you for this bug report. To properly diagnose the problem, we
need a short but complete example script to be able to reproduce
this bug ourselves. 

A proper reproducing script starts with <?php and ends with ?>,
is max. 10-20 lines long and does not require any external 
resources such as databases, etc. If the script requires a 
database to demonstrate the issue, please make sure it creates 
all necessary tables, stored procedures etc.

Please avoid embedding huge scripts into the report.

<?php
$i=0;
$test2=array(
   'a1_teasermenu' => array(
   		'downloadcounter' => 2777,
        'versions' => array(
        	'0.1.0' => array (
        		'title' => 'A1 Teasermenu',
        	    'description' => 'Displays a teaser for advanced subpages or a selection of advanced pages',
        	    'state' => 'stable',
        	    'reviewstate' => 0,
        	    'category' => 'plugin',
        	    'downloadcounter' => 2787,
        	    'lastuploaddate' => 1088427240,
        	    'dependencies' => array (
        	          'depends' => array(
        	                  'typo3' =>'', 
        	                  'php' =>'', 
        	                  'cms' => ''
        	           ),        	
        	          'conflicts' => array('' =>'')        	
        	    ),        	
        	  	'authorname' => 'Mirko Balluff',
        	  	'authoremail' => 'balluff@amt1.de',
        	  	'ownerusername' => 'amt1',
        	  	't3xfilemd5' => '3a4ec198b6ea8d0bc2d69d9b7400398f',
      		)
  		)
  	)
);
$test=array();
while($i<1600) {	
	$test[]=$test2;
	$i++;
}
$out=gzcompress(serialize($test));
?>

results in :
PHP Fatal error:  Allowed memory size of 67108864 bytes exhausted at /usr/pkgsrc/lang/php5/work/php-5.2.0/ext/standard/var.c:541 (tried to allocate 1041720 bytes) in /var/www/www.chaosbutze.de/htdocs/test2.php on line 37

while it works on php 5.1.6 and 4.
Having mem limit set to 64MB.

Setting mem limit to 128MB and increasing interations to 2260 also causes the above mentioned error.

Did some further testing:
the script worked on:
PHP 5.1.6-5 (cli) (built: Oct 28 2006 13:49:33) Memlimit:8mb
PHP 5.1.6-5 (cli) (built: Oct 28 2006 13:49:33) Memlimit:64MB

Are there current any work arounds for this problem?
My host has upgraded to 5.2.0, so I'm stuck with this problem.

No workarounds atm i had to downgrade :|

I had this problem with my forum, after some time it showed:

Fatal error: Out of memory (allocated 786432) (tried to allocate 1572864 bytes)

I tried to set memory_limit from 16M to 64M, and it didn't work.

I've downgraded to 5.1.6

Just for info: I've experienced memory usage bumping since 
somewhere after 5.2.0RC2 and current CVS.
(phpDocumentor needs more than 256M with 5.2.1-dev, but 
not with 5.2.0RC3-dev)

I started receiving this error on my WordPress blog since I upgraded to php 5.2.0 from 5.1.6, but seems that after a refresh it goes away (running on FastCGI on Apache). Sometimes it requires a few refreshes for it to go away, but it is never too constant.

I withdraw my previous comment, the RC3-build was 
without "--enable-memory-limit". Sorry.

I've found that
---------------------------------------
<?php
$i = 0;
$a = array();
while( $i++ < 100000 )
{
        $a[] = 'a';
}
echo memory_get_usage();
?>
---------------------------------------
uses a lot more memory. I cannot say, if this is because 
of the more accurate memory manager reporting.

I'm surprised how much memory is needed for 100.000 "a"'s 
in an array..


$ php -f test2.php
9494860
daniel@base [stp:2] { ~/bugs/php/memoryusage }
$ php5 -f test2.php
6967216

--------

$ php -v
PHP 5.2.1-dev (cli) (built: Nov 27 2006 03:16:44)
Copyright (c) 1997-2006 The PHP Group
Zend Engine v2.2.0, Copyright (c) 1998-2006 Zend 
Technologies

$ php5 -v
PHP 5.1.6 (cli) (built: Nov  2 2006 12:49:10)
Copyright (c) 1997-2006 The PHP Group
Zend Engine v2.1.0, Copyright (c) 1998-2006 Zend 
Technologies

Fixed in CVS HEAD and PHP_5_2.