From:             flavius dot as at gmail dot com
Operating system: Linux
PHP version:      5.3.1
PHP Bug Type:     *Programming Data Structures
Bug description:  serialize() crashes with unreasonable/unexplicable "out of 
memory" for objects

Description:
------------
When serializing a SplFixedArray with serialize(), the script dies with
"Fatal error: Allowed memory size of 134217728 bytes exhausted"

The "expected result" works and allocates at most 20.96 mb for $cnt = 8565
on line 15.

The "actual result" crashes when serialize()'ing with $cnt only
incremented by one, which is not understandable.

The actual values may vary, but if you play enough with it you'll find at
which amount of items serialize() has that spark.

Then you can toggle to using plain arrays on line 17, and that problem
will disappear, although arrays actually consume more memory (in my
experiments around 1.2 mb more).

Reproduce code:
---------------
     1  <?php
     2  function rand_str($length = 32, $chars =
'ABCDEFGHIJKLMNOPQRSTUVWXYZ abcdefghijklmnopqrstuvwxyz1234567890') {
     3      $chars_length = (strlen($chars) - 1);
     4      $string = $chars{rand(0, $chars_length)};
     5      for ($i = 1; $i < $length; $i = strlen($string)) {
     6          $r = $chars{rand(0, $chars_length)};
     7          if ($r != $string{$i - 1}) $string .=  $r;
     8      }
     9      return $string;
    10  }
    11  function convert($size) {
    12      $units=array('b','kb','mb','gb','tb','pb');
    13      return
@round($size/pow(1024,($unit=floor(log($size,1024)))),2).'
'.$units[$unit];
    14  }
    15  $cnt = 8566;
    16  $r = new SplFixedArray($cnt);
    17  //$r = array();
    18  for($i=0;$i<$cnt;$i++) {
    19          $r[$i] = rand_str(1024);
    20  }
    21  echo "\nGENERATING DONE\n";
    22  echo 'peak before serialize()
',convert(memory_get_peak_usage()),PHP_EOL;
    23  echo "---\n";
    24  $r = serialize($r);
    25  echo 'peak after dumping
',convert(memory_get_peak_usage()),PHP_EOL;
    26  unset($r);


Expected result:
----------------
GENERATING DONE
peak before serialize() 10.19 mb
---
peak after dumping 20.96 mb


Actual result:
--------------
GENERATING DONE
peak before serialize() 10.19 mb
---

Fatal error: Allowed memory size of 134217728 bytes exhausted (tried to
allocate 8913127 bytes) in /home/flav/softpedia/bigarray-bugreport.php on
line 24


-- 
Edit bug report at http://bugs.php.net/?id=51155&edit=1
-- 
Try a snapshot (PHP 5.2):            
http://bugs.php.net/fix.php?id=51155&r=trysnapshot52
Try a snapshot (PHP 5.3):            
http://bugs.php.net/fix.php?id=51155&r=trysnapshot53
Try a snapshot (PHP 6.0):            
http://bugs.php.net/fix.php?id=51155&r=trysnapshot60
Fixed in SVN:                        
http://bugs.php.net/fix.php?id=51155&r=fixed
Fixed in SVN and need be documented: 
http://bugs.php.net/fix.php?id=51155&r=needdocs
Fixed in release:                    
http://bugs.php.net/fix.php?id=51155&r=alreadyfixed
Need backtrace:                      
http://bugs.php.net/fix.php?id=51155&r=needtrace
Need Reproduce Script:               
http://bugs.php.net/fix.php?id=51155&r=needscript
Try newer version:                   
http://bugs.php.net/fix.php?id=51155&r=oldversion
Not developer issue:                 
http://bugs.php.net/fix.php?id=51155&r=support
Expected behavior:                   
http://bugs.php.net/fix.php?id=51155&r=notwrong
Not enough info:                     
http://bugs.php.net/fix.php?id=51155&r=notenoughinfo
Submitted twice:                     
http://bugs.php.net/fix.php?id=51155&r=submittedtwice
register_globals:                    
http://bugs.php.net/fix.php?id=51155&r=globals
PHP 4 support discontinued:          http://bugs.php.net/fix.php?id=51155&r=php4
Daylight Savings:                    http://bugs.php.net/fix.php?id=51155&r=dst
IIS Stability:                       
http://bugs.php.net/fix.php?id=51155&r=isapi
Install GNU Sed:                     
http://bugs.php.net/fix.php?id=51155&r=gnused
Floating point limitations:          
http://bugs.php.net/fix.php?id=51155&r=float
No Zend Extensions:                  
http://bugs.php.net/fix.php?id=51155&r=nozend
MySQL Configuration Error:           
http://bugs.php.net/fix.php?id=51155&r=mysqlcfg

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