public function startProfiling()
    {
        if (PHP_SAPI == 'cli') {
            $_SERVER['REMOTE_ADDR'] = null;
            $_SERVER['REQUEST_URI'] = $_SERVER['SCRIPT_NAME'];
        }

        if (function_exists('xhprof_enable') && count($this->probes) > 0) {
            $this->profiling = true;
            xhprof_enable($this->memory ? XHPROF_FLAGS_MEMORY : null);
        }
    }