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