程序：

while(1):     # query tasks from local file     if task:         publish(video_id)     else:         sleep(1)

长时间运行后，会报出以下错误，这是啥意思？

Traceback (most recent call last):   File "publisher_dev.py", line 209, in <module>     publish(video_id)   File "publisher_dev.py", line 157, in publish     delivery_mode=2,  # make message persistent   File "/home/weike/.local/lib/python2.7/site-packages/pika/adapters/blocking_connection.py", line 1978, in basic_publish     mandatory, immediate)   File "/home/weike/.local/lib/python2.7/site-packages/pika/adapters/blocking_connection.py", line 2065, in publish     self._flush_output()   File "/home/weike/.local/lib/python2.7/site-packages/pika/adapters/blocking_connection.py", line 1174, in _flush_output     *waiters)   File "/home/weike/.local/lib/python2.7/site-packages/pika/adapters/blocking_connection.py", line 395, in _flush_output     raise exceptions.ConnectionClosed() pika.exceptions.ConnectionClosed