'constructor'

def __init__(self, fetcher, parser, saver, url_filter=None, monitor_sleep_time=5):

    BasePool.__init__(self, fetcher, parser, saver, url_filter=url_filter)
    self._fetch_queue = queue.PriorityQueue()
    self._parse_queue = queue.PriorityQueue()
    self._save_queue = queue.Queue()
    self._lock = threading.Lock()
    self._monitor_stop = False
    self._monitor = MonitorThread('monitor', self, sleep_time=monitor_sleep_time)
    self._monitor.setDaemon(True)
    self._monitor.start()
    return
