private function logRequestHeaders()
    {
        if (!$this->debug->getCfg('logEnvInfo.headers')) {
            return;
        }
        if (!empty($_SERVER['argv'])) {
            return;
        }
        $headers = $this->debug->utilities->getAllHeaders();
        \ksort($headers, SORT_NATURAL);
        $this->debug->log('request headers', $headers);
    }