private function checkStatus()
    {
        if (!$this->running) {
            return;
        }

        if ($this->running) {
            foreach (proc_get_status($this->resource) as $key => $value) {
                if ($key == 'command') {
                    continue;
                }

                $this->$key = $value;
            }
        }

        if (!$this->running) {
            $this->cleanup();
        }
    }