Memory leak in PHP using PDO::FETCH_ASSOC on MySQL query

Memory is leaking in a script am working on. On local server it works fine but on the remote server memory leaks. I can’t find the cause of the memory leak.

The error message is:

PHP Fatal error:  Allowed memory size of 67108864 bytes exhausted (tried to allocate 50 bytes) in database.php on line 21

Configuration of local host:

• PHP 5.4.3
• MySQL 5.5.24
• Apache 2.4.2

Configuration of remote host:

• PHP 5.4.7
• MySQL 5.5.34
• Apache 2.2.23

Code triggering the error:

//database.php

class Database {
    public function __construct() {
        $hostname = DB_HOST;
        $dbname = DB_NAME;
        $username = DB_USER;
        $dbpass = DB_PASS;
        try {
            $this->dbh = new PDO("mysql:host=$hostname;dbname=$dbname;charset=utf8", $username, $dbpass);
        } catch (PDOException $e) {
            echo $e->getmessage();
        }
    }

    public function get_data($query, $param = array()) {
            $result = array();
            $stmt = $this->dbh->prepare($query);
            $stmt->execute($param);
            while ($row = $stmt->fetch(PDO::FETCH_ASSOC)) // this is line 21
            {
                    $result[] = $row;
            }
            return $result;
    }
}

//getusers.php

class getusers {
    public function __construct($dataparam) {
        $this->_db = new Database();
        $this->getmyUsers();
    }

    protected function getmyUsers() {
        $this->myquery = "SELECT name,phone,email,address,company,regdate FROM myusers WHERE user_status=:stat ORDER BY regdate DESC LIMIT 0, 50";
        $this->myparam = array(':stat' => 'on');
        return $this->_db->get_data($this->myquery, $this->myparam);
    }
}

//I ran a test fetching 30 rows

                 $result = array();

        $stmt = $this->dbh->prepare($query);
        $memory_end_one = 0;
        $memory_start_one = memory_get_usage();
        $stmt->execute($param);

        while($row = $stmt->fetch(PDO::FETCH_ASSOC))
        {
        $result[] = $row;
        $memory_end_one = max($memory_end_one, memory_get_usage());
        }
        echo 'initial memory: '.$memory_start_one.'b<br />';
        echo 'Final memory: '. ($memory_end_one - $memory_start_one).'b<br/>';exit();

Results For remote server

• Initial memory: 216028b
• Final memory: 178700b

For local server

• Initial memory: 413664b
• Final memory: 172632b