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Bug #52487 PDO::FETCH_INTO leaks memory
Submitted: 2010-07-29 15:47 UTC Modified: 2010-07-30 01:39 UTC
From: marques at displague dot com Assigned: felipe
Status: Closed Package: PDO related
PHP Version: 5.3.3 OS:
Private report: No CVE-ID:
 [2010-07-29 15:47 UTC] marques at displague dot com
Description:
------------
When assigning an object to a PDO statement via FETCH_INTO a memory leak occurs 
that can not be corrected through php code.  A subsequent FETCH_INTO with a 
different object only furthers the problem.  Changing the fetch mode, unsetting 
the statement, closing the cursor, and calling the garbage collection do not free 
the memory either. 

This bug exists in 5.2 and 5.3.

Test script:
---------------
<?php
if (! extension_loaded('pdo_sqlite')) {
	dl('pdo_sqlite.so');
}
$pdo = new PDO('sqlite::memory:');
echo "Start mem:".memory_get_peak_usage()."\n";

// Simple test
$stmt = $pdo->prepare("select 1 as attr");
for($i=0; $i<100000; $i++) {
	$stmt->setFetchMode(PDO::FETCH_INTO, new StdClass);
	echo "mem: ".memory_get_usage()."\n";

}
// End - Simple Test

// Alternate test with failed remedies
class test {
	public $attr;
	public function load($pdo) {
		$stmt = $pdo->prepare("select 1 as attr");
		//$stmt->setFetchMode(PDO::FETCH_INTO, $this); // This leaks quickly
		$stmt->setFetchMode(PDO::FETCH_INTO, new StdClass); // This still leaks
		$stmt->setFetchMode(PDO::FETCH_ASSOC); // You might think this would fix the leak - no effect
		$stmt->closeCursor(); // No effect
		unset($stmt); // No effect
	}
}

for($i=0; $i<100000; $i++) {
	$test = new test;
	$test->load($pdo);
	if (function_exists('gc_collect_cycles')) {
		echo "+gc+ ";
		gc_collect_cycles(); // No effect
	}
	unset($test);
	echo "mem: ".memory_get_peak_usage()."\n";
}



Expected result:
----------------
I would expect the peak memory usage to remain consisten on subsequent iterations.

Actual result:
--------------
The peak memory usage continues to rise until the php memory limit is hit.

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History

AllCommentsChangesGit/SVN commitsRelated reports
 [2010-07-30 01:38 UTC] felipe@php.net
Automatic comment from SVN on behalf of felipe
Revision: http://svn.php.net/viewvc/?view=revision&amp;revision=301706
Log: - Fixed bug #52487 (PDO::FETCH_INTO leaks memory)
 [2010-07-30 01:39 UTC] felipe@php.net
-Status: Open +Status: Closed -Assigned To: +Assigned To: felipe
 [2010-07-30 01:39 UTC] felipe@php.net
This bug has been fixed in SVN.

Snapshots of the sources are packaged every three hours; this change
will be in the next snapshot. You can grab the snapshot at
http://snaps.php.net/.
 
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