protected function expireResponses()
    {
        $now = TimeSupport::now();
        $expiredReps = [];

        foreach ($this->handledReps as $pid=>$response)
        {
            if ($now >= $response->timeout)
            {
                $expiredReps[] = $pid;
            }
        }

        foreach ($expiredReps as $pid)
        {
            unset($this->handledReps[$pid]);
        }
    }