Please provide a _complete_ script for testing. Also mind that increasing memory_get_usage() values don't necessarily represent memory leaks but includes different cache data or memory which will be re-used.

A complete script was requested. To run the test you will need some mysql tables. I can provide sanitized versions of production data. Please advise as to how to upload.

Here is the script.

<?php
/**
 * Title:		Test Autoemail Memory
 * Author:		JAS
 * Date:		11-May-10
 * Project:		RepHunter
 * Purpose:		Testing memory leak
 *
 */

define('MYSQL_ENHANCED', true);
require('../site.php');	// site specific parameter file outside the web root
$link = open_db($DBNAME, $DBHOSTNAME, $DBUSER, $DBPASSWORD);

echo "Test Autoemail Memory Leak\n";
echo 'Using ' . (MYSQL_ENHANCED ? 'mysqli_connect' : 'mysql_connect') . "\n";
echo 'start run mem=' . memory_get_usage(true) . "\n";
$query = get_query();
$rs = SQL($link, $query);
if ($rs)
{
	// main loop
	$cnt = 0;
	echo 'after SQL mem=' . memory_get_usage(true) . "\n";
	$func = (MYSQL_ENHANCED) ? 'mysqli_fetch_row' : 'mysql_fetch_row';
	while($row = $func($rs))
	{
		if (++$cnt % 3000 == 0)
		{
			echo '   id=' . $row[1] . '  mem=' . memory_get_usage(true) . "\n";
			// gc_collect_cycles();
		}
		// unset($row);
		// $row = null;
	}
	echo "EOJ\n";
}
else
{
	echo $errmsg;
}


function open_db($DBNAME, $DBHOSTNAME, $DBUSER, $DBPASSWORD)
{
	if (MYSQL_ENHANCED)
	{
		$link = mysqli_connect($DBHOSTNAME, $DBUSER, $DBPASSWORD, $DBNAME);
		if(!$link)
		{
		    trigger_error('Cannot connect to mysql', E_USER_ERROR);
		}
	}
	else
	{
		$link = mysql_connect($DBHOSTNAME, $DBUSER, $DBPASSWORD);
		if(!$link)
		{
		    trigger_error('Cannot connect to mysql', E_USER_ERROR);
		}
		$db_selected = mysql_select_db($DBNAME, $link);
		if (!$db_selected)
		{
		    trigger_error('Cannot use ' . $DBNAME . ': '. mysql_error($link), E_USER_ERROR);
		}
	}
	return $link;
}


function SQL($link, $query)
{
	global $errmsg;

	if (MYSQL_ENHANCED)
	{
		$rs = mysqli_query($link, $query);
		if (!$rs)
		{
			$errmsg = mysqli_errno($link) . ': ' . mysqli_error($link);
			return false;
		}
	}
	else
	{
		$rs = mysql_query($query, $link);
		if (!$rs)
		{
			$errmsg = mysql_errno($link) . ': ' . mysql_error($link);
			return false;
		}
	}
	return $rs;
}

function get_query()
{
	return <<<SQL
	SELECT
		u.usertypeid,
		u.userid,
		opt_out,
		DATE_FORMAT(dateentry, '%Y/%m/%d'),
		DATE_FORMAT(dateentry, '%m/%d/%Y'),
		DATE_FORMAT(dateupdate, '%Y/%m/%d'),
		DATE_FORMAT(dateupdate, '%m/%d/%Y %h:%i %p'),
		referrerid,
		referralcnt,
		phone1,
		email1,
		u.status,
		DATE_FORMAT(datestatus, '%Y/%m/%d'),
		0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, '','','','','','','','','',''
		, fname, lname, address1, address2, city, state, postal
	FROM user u


	WHERE u.status NOT IN ('R')

UNION

	SELECT
		6 AS usertypeid,
		c.repid,
		opt_out,
		DATE_FORMAT(dateentry, '%Y/%m/%d'),
		DATE_FORMAT(dateentry, '%m/%d/%Y'),
		DATE_FORMAT(dateupdate, '%Y/%m/%d'),
		DATE_FORMAT(dateupdate, '%m/%d/%Y %h:%i %p'),
		referrerid,
		referralcnt,
		phone1,
		email1,
		u.status,
		DATE_FORMAT(datestatus, '%Y/%m/%d'),
		0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, '','','','','','','','','',''
		, '', '', '', '', '', '', ''
	FROM contactrequest c
		LEFT OUTER JOIN user u ON u.userid = c.repid

	WHERE Response = ''
		AND initiatedby = 2
		AND u.status NOT IN ('R', 'I', 'U')
	GROUP BY c.repid, email1, fname, u.userid, referrerid, referralcnt

UNION

	SELECT
		7 as usertypeid,
		c.principalid,
		opt_out,
		DATE_FORMAT(dateentry, '%Y/%m/%d'),
		DATE_FORMAT(dateentry, '%m/%d/%Y'),
		DATE_FORMAT(dateupdate, '%Y/%m/%d'),
		DATE_FORMAT(dateupdate, '%m/%d/%Y %h:%i %p'),
		referrerid,
		referralcnt,
		phone1,
		email1,
		u.status,
		DATE_FORMAT(datestatus, '%Y/%m/%d'),
		0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, '','','','','','','','','',''
		, '', '', '', '', '', '', ''
	FROM contactrequest c
		LEFT OUTER JOIN user u ON u.userid = c.principalid

	WHERE Response = ''
		AND initiatedby = 1
		AND u.status NOT IN ('R', 'I', 'U')
	GROUP BY c.principalid, email1, fname, u.userid, referrerid, referralcnt

UNION

	SELECT
		8 AS usertypeid,
		u.userid,
		opt_out,
		DATE_FORMAT(dateentry, '%Y/%m/%d'),
		DATE_FORMAT(dateentry, '%m/%d/%Y'),
		DATE_FORMAT(dateupdate, '%Y/%m/%d'),
		DATE_FORMAT(dateupdate, '%m/%d/%Y %h:%i %p'),
		referrerid,
		referralcnt,
		phone1,
		email1,
		status,
		DATE_FORMAT(datestatus, '%Y/%m/%d'),
		0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, '','','','','','','','','',''
		, fname, lname, address1, address2, city, state, postal
	FROM paidpridtl d
		INNER JOIN user u ON u.userid = d.userid

	WHERE planid IN (103, 104, 94, 1, 93)
		AND d.datestart > DATE_ADD(CURDATE(), INTERVAL 5 - 1 DAY)
		AND d.datestart <= DATE_ADD(CURDATE(), INTERVAL 5 DAY)

UNION

	SELECT
		12 as usertypeid,
		u.userid,
		opt_out,
		DATE_FORMAT(dateentry, '%Y/%m/%d'),
		DATE_FORMAT(dateentry, '%m/%d/%Y'),
		DATE_FORMAT(dateupdate, '%Y/%m/%d'),
		DATE_FORMAT(dateupdate, '%m/%d/%Y %h:%i %p'),
		referrerid,
		referralcnt,
		phone1,
		email1,
		u.status,
		DATE_FORMAT(datestatus, '%Y/%m/%d'),
		0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, '','','','','','','','','',''
		, fname, lname, address1, address2, city, state, postal
	FROM user u


	WHERE u.status NOT IN ('R')
		AND profile_complete & 7 <> 7 ORDER BY userid DESC
SQL;
}

Hi,
I suppose there is no problem but the following occurs. Before 5.3 PHP used libmysql as underlying library. Since 5.3 there is an option to use PHP's implementation of the client/server protocol, the mysqlnd library. This library uses PHP's memory allocation functions, thus affects memory_get_usage(). When you used libmysql and it allocated memory, this memory wasn't reported by memory_get_usage() because the latter counts only the memory allocated by the PHP's memory allocator.
To see if there is really a leak, you have to free your result sets and then dereference all the variables which point to the result set. If the memory usage is still high, there could be a problem. There is no problem, if you have created big SQL statement and later the reported used memory is still high, because mysqlnd has a buffer onto which data packets are created. When big SQL statement comes, the buffer needs to be enlarged and later it is not made smaller.

No feedback was provided. The bug is being suspended because
we assume that you are no longer experiencing the problem.
If this is not the case and you are able to provide the
information that was requested earlier, please do so and
change the status of the bug back to "Open". Thank you.

Reproduced the memory leakage in php 5.5.0 + win7
had to fetch through 10M lines of TINYTEXT string (randoms from 4 to 250 utf8 chars)

$pt = mysql_query("SELECT tinytext_data, int_primkey FROM buffer");
while ($line = mysql_fetch_array($pt))
{
  //doesnt need to do anything
  echo "\r\n". memory_get_usage();
}

at each step, it increase the mem usage by 64 bytes, never freeing them.

Note : same leakage using mysql_fetch_row() or mysql_fetch_array()

I run into the same problem as well. I use mysqli_query() and on each execution it increases by 50 or so bytes. I unset the crap out of everything and do mysqli_free_result() but still the number keeps rising.

I am the OP for this ticket. Our system, now at PHP 5.6.9, is once again experiencing a memory leak, and in fact it is in the same script as in the original post.

I am planning to do some testing to see if unsetting things helps. But per the post from yesterday from supraguy, that does not work.

The problem seems to be worse than previously. The following results are on PHP 5.5.27.

On every loop while reading a table, memory is consumed, regardless of using gc_enable, unset, or mysqli_free_memory.

I started by dusting off the script that I originally provided in this bug ticket on 2011-07-05. However that complexity is not needed, and a very simple query of "SELECT * from user" gives the same result.

Here is the main loop of the simplified version, where the user table has about 70,000 rows:

$rs = mysqli_query($link, 'SELECT * FROM user');

if ($rs)
{
	// main loop
	$cnt = 0;
	echo 'after SQL mem=', memory_get_usage(true), LF;
	while($row = mysqli_fetch_row($rs))
	{
		if (++$cnt % 3000 == 0)
		{
			echo '   id=', $row[$userid_ix], '  mem=', memory_get_usage(true), LF;
			gc_collect_cycles();
			flush();
			ob_flush();	// documentation is inconclusive whether this is also needed
		}
		unset($row);
		// $row = null;
	}
}

Here is the output of the above script (please note that the echo statements are issued once for every 3000 rows):

Test Autoemail Memory Leak
Using mysqli_connect
start run mem=524288
Query
SELECT * FROM user
after SQL mem=24117248
   id=3043  mem=29884416
   id=6066  mem=35913728
   id=9041  mem=41680896
   id=12031  mem=47710208
   id=15015  mem=53477376
   id=17986  mem=59506688
   id=20984  mem=65273856
   id=24004  mem=71303168
   id=27065  mem=77070336
   id=30076  mem=83099648
   id=33115  mem=88866816
   id=36201  mem=94896128
   id=39095  mem=100663296
   id=42106  mem=106692608
   id=45112  mem=112459776
   id=48104  mem=118489088
   id=51085  mem=124518400
   id=54082  mem=130285568
PHP Fatal error:  Allowed memory size of 134217728 bytes exhausted (tried to allocate 32 bytes) in /Users/jas/Websites/RepHunter/current/test-autoemail-memory.php on line 44

The various attempts to reclaim memory (gc_enable(), unset(), gc_reclaim_cycles, and setting the $row to null, all have no effect. 

At this point, the workaround is to simply set memory large enough, and hope the application completes before exhausting memory. At present I am using ini_set('memory_limit', '384M');

The problem (on line 44) is while($row = mysqli_fetch_row($rs)).

Has anybody come up with an alternative to that construct that does not continue to consume memory?

Please note that in my above post with the simplified code, the flush() and ob_flush() are not directly related to the issue afaik, but have to do with attempts to display output in a browser.

By default, mysqli uses buffered result sets, so your entire result set will be kept in memory. Disabling this is very simple: Pass MYSQLI_USE_RESULT to mysqli_query(). In this case, I have confirmed that memory usage for the provided test case stays constant.