前段時間，專案裡用到python-nfqueue，但是遇到一個問題，當網卡里沒有資料時，監控執行緒被阻塞。話不多說，先來一段程式碼：

t2 = threading.Thread(target=self.start_nfqueue)
t2.daemon = True
t2.start()　　　＃＃＃　啟動nfqueue

p = threading.Thread(target=self.check_dev_status, args=('130.0.0.50', 7313))
p.daemon = True
p.start()  ### 啟動監控執行緒

def start_nfqueue(self
 
):
    print "setting callback"
q.set_callback(cb)

    print "creating queue"
q.create_queue(0)

    q.set_queue_maxlen(50000)

    print "trying to run"
try:
        q.try_run()
    except KeyboardInterrupt, e:
        print "interrupted"
print "unbind"
q.unbind(AF_INET)

    print "close"
q.close()

被這個問題困擾了幾天，翻了下nfqueue原始碼，發現一個非同步介面asyncore，直接上程式碼：

def start_nfqueue(self):
    self.async_queue = AsyncNfQueue(self.cb)
    asyncore.loop()

class AsyncNfQueue(asyncore.file_dispatcher):
    def __init__(self, cb, nqueue=0, family=AF_INET, maxlen=5000, map=None):
        self._q = nfqueue.queue()
        self._q.set_callback(cb)
        self._q.fast_open(nqueue, 
 
family)
        self._q.set_queue_maxlen(maxlen)
        self.fd = self._q.get_fd()
        asyncore.file_dispatcher.__init__(self, self.fd, map)
        self._q.set_mode(nfqueue.NFQNL_COPY_PACKET)

    def handle_read(self):
        print "Processing at most 5 events"
self._q.process_pending(5)

    def writable(self):
        return False

至此，問題解決。