Unbuffered queries error in mysql, pdo config doesn't working, every third query returns empty data

Hi!

Situation

I'm using MySQL and Phalcon 2.0.9 and have this snippet in my Models\Base:

    /**
     * @param string $sql
     * @param array  $params
     *
     * @return Resultset\Simple
     */
    public static function findByRawSql($sql, array $params = [])
    {
        $self = new static;
        try {
            /**
             * @type \Phalcon\Db\Adapter\Pdo $conn
             * @type \Phalcon\Db\Result\Pdo  $query
             */
            $conn   = $self->getReadConnection();
            $query  = $conn->query($sql, $params);
            $result = new Resultset\Simple(null, $self, $query);
        }
        catch (\PDOException $e) {
            return false;
        }

        return $result;
    }

What i do

Then i do in my Models\User:

$friends = static::findByRawSql('CALL GetUserFriends(:id)', ['id' => $this->id]);

But have PDOException:

SQLSTATE[HY000]: General error: 2014 Cannot execute queries while other unbuffered queries are active. Consider using PDOStatement::fetchAll(). Alternatively, if your code is only ever going to run against mysql, you may enable query buffering by setting the PDO::MYSQL_ATTR_USE_BUFFERED_QUERY attribute.

Solvings and problems

I've googled about this and PDO::MYSQL_ATTR_USE_BUFFERED_QUERY doesn't help. If i do fetchAll then i can't use Resultset.

Plus, i can't explain this case:

1. Send request to my site – in controller do: $friends = static::findByRawSql("CALL GetUserFriends(:id)", ["id" => $this->id]); – all is OK – array of arrays with users data
2. Repeat step no.1 – all is OK – same
3. Repeat step no.1 one more time (third) – FAIL – empty array.

Repeats only if i use findByRawSql – other requests to databse working everytime and returning same values.

Questions

So my questions are simple:

1. How can i use Resultset and not getting into this error?
2. Why PDO configuration doesn't work?
3. Why findByRawSql returns different empty result every third query? o.0