ConnectionError: Error while reading from socket: ('Connection closed by server.',)

[vontio]

redis-monitor.py throw exception after run in some minutes

Exception in thread Thread-1:
Traceback (most recent call last):
File "/usr/lib/python2.7/threading.py", line 810, in __bootstrap_inner
self.run()
File "./redis-monitor.py", line 103, in run
for command in commands:
File "./redis-monitor.py", line 59, in listen
yield self.parse_response()
File "./redis-monitor.py", line 53, in parse_response
return self.connection.read_response()
File "/usr/local/lib/python2.7/dist-packages/redis/connection.py", line 569, in read_response
response = self._parser.read_response()
File "/usr/local/lib/python2.7/dist-packages/redis/connection.py", line 224, in read_response
response = self._buffer.readline()
File "/usr/local/lib/python2.7/dist-packages/redis/connection.py", line 162, in readline
self._read_from_socket()
File "/usr/local/lib/python2.7/dist-packages/redis/connection.py", line 137, in _read_from_socket
(e.args,))
ConnectionError: Error while reading from socket: ('Connection closed by server.',)