php递归罗致内存不够

$user = 'root';
$pass = 'thrope';
$dbh = new PDO('mysql:host=localhost;dbname=income', $user, $pass);
$query = 'insert into picinfo set picpath=:pp, picsize=:ps';//把文件路径和文件大小写入数据库
$stmt = $dbh->prepare($query);

function dir_read($dir){
	$dh = opendir($dir);//if (is_dir($dir)) echo realpath($dir).'
';
	while (false !== ($filename = readdir($dh))){//echo realpath($dir.'/'.$filename).'
';
		//if ($filename == '.' || $filename == '..') continue;
		if (is_file($dir.'/'.$filename)){
			global $stmt;
			$stmt->execute(array(':pp'=>realpath($dir.'/'.$filename), ':ps'=>filesize(realpath($dir.'/'.$filename))));
			//echo $dbh->errorCode();
		}
		if (is_dir(realpath($dir.'/'.$filename)))//这个递归调用特别耗费资源
			dir_read(realpath($dir.'/'.$filename));
		
	}
	closedir($dh);
}

dir_read('K:/project/fileOperate');