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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 (profile)
Status: Closed Package: PDO related
PHP Version: 5.3.3 OS:
Private report: No CVE-ID: None
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 [2010-07-29 15:47 UTC] marques at displague dot com
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:
if (! extension_loaded('pdo_sqlite')) {
$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;
	if (function_exists('gc_collect_cycles')) {
		echo "+gc+ ";
		gc_collect_cycles(); // No effect
	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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 [2010-07-30 01:38 UTC]
Automatic comment from SVN on behalf of felipe
Log: - Fixed bug #52487 (PDO::FETCH_INTO leaks memory)
 [2010-07-30 01:39 UTC]
-Status: Open +Status: Closed -Assigned To: +Assigned To: felipe
 [2010-07-30 01:39 UTC]
This bug has been fixed in SVN.

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