Redisでパブサブシステムを作るとエラーが起きる

Question

###質問内容
オライリー発行の「入門Python3」を学んでいるのですが，p.349にある，Redisを用いたパブサブシステムをそのまま写したのにエラーが吐かれてしまい，うまく動作しません．どのようにすればエラーを解決することが出来ますでしょうか．
pip3 install redisは行いました．
実行結果とコードは以下に載せます

###pub.py

import redis
import random

conn = redis.Redis()
cats = ["siamese", "persian", "maine coon", "norweigan forest"]
hats = ["stovepipe", "bowler", "tam-o-shnter", "fadora"]
for msg in range(10):
    cat = random.choice(cats)
    hat = random.choice(hats)
    print("Publish: %s wears a %s" % (cat, hat))
    conn.publish(cat, hat)

###sub.py

import redis

conn = redis.Redis()

topics = ["maine coon", "persian"]
sub = conn.pubsub()
sub.subscribe(topics)
for msg in sub.listen():
    if msg["type"] == "message":
        cat = msg["channel"]
        hat = msg["data"]
        print("Subscribe: %s wears a %s" % (cat, hat))

###実行結果

~/work/python/ch11$ python3 sub.py
Traceback (most recent call last):
  File "/home/.local/lib/python3.8/site-packages/redis/connection.py", line 559, in connect
    sock = self._connect()
  File "/home/.local/lib/python3.8/site-packages/redis/connection.py", line 615, in _connect
    raise err
  File "/home/.local/lib/python3.8/site-packages/redis/connection.py", line 603, in _connect
    sock.connect(socket_address)
ConnectionRefusedError: [Errno 111] Connection refused

During handling of the above exception, another exception occurred:

Traceback (most recent call last):
  File "sub.py", line 7, in <module>
    sub.subscribe(topics)
  File "/home/.local/lib/python3.8/site-packages/redis/client.py", line 3580, in subscribe
    ret_val = self.execute_command('SUBSCRIBE', *iterkeys(new_channels))
  File "/home/.local/lib/python3.8/site-packages/redis/client.py", line 3466, in execute_command
    self.connection = self.connection_pool.get_connection(
  File "/home/.local/lib/python3.8/site-packages/redis/connection.py", line 1192, in get_connection
    connection.connect()
  File "/home/.local/lib/python3.8/site-packages/redis/connection.py", line 563, in connect
    raise ConnectionError(self._error_message(e))
redis.exceptions.ConnectionError: Error 111 connecting to localhost:6379. Connection refused.

~/work/python/ch11$ python3 pub.py
Publish: persian wears a bowler
Traceback (most recent call last):
  File "/home/.local/lib/python3.8/site-packages/redis/connection.py", line 559, in connect
    sock = self._connect()
  File "/home/.local/lib/python3.8/site-packages/redis/connection.py", line 615, in _connect
    raise err
  File "/home/.local/lib/python3.8/site-packages/redis/connection.py", line 603, in _connect
    sock.connect(socket_address)
ConnectionRefusedError: [Errno 111] Connection refused

During handling of the above exception, another exception occurred:

Traceback (most recent call last):
  File "pub.py", line 11, in <module>
    conn.publish(cat, hat)
  File "/home/.local/lib/python3.8/site-packages/redis/client.py", line 3098, in publish
    return self.execute_command('PUBLISH', channel, message)
  File "/home/.local/lib/python3.8/site-packages/redis/client.py", line 898, in execute_command
    conn = self.connection or pool.get_connection(command_name, **options)
  File "/home/.local/lib/python3.8/site-packages/redis/connection.py", line 1192, in get_connection
    connection.connect()
  File "/home/.local/lib/python3.8/site-packages/redis/connection.py", line 563, in connect
    raise ConnectionError(self._error_message(e))
redis.exceptions.ConnectionError: Error 111 connecting to localhost:6379. Connection refused.

Comments

[退会済みユーザー]

Redisが立ち上がっていないか、ポート番号が6379以外で動いているのでは？

[grape_ll]

Redisを立ち上げるとは，redis-serverのことでしょうか．先ほど調べたので質問時点では行っていませんでした．実行してみたところ，下記のようになってしまって，python3 pub.pyのような実行が出来なくってしまいました．

redis-server
687:C 24 Mar 2021 15:11:00.658 # oO0OoO0OoO0Oo Redis is starting oO0OoO0OoO0Oo
687:C 24 Mar 2021 15:11:00.658 # Redis version=5.0.7, bits=64, commit=00000000, modified=0, pid=687, just started
687:C 24 Mar 2021 15:11:00.658 # Warning: no config file specified, using the default config. In order to specify a config file use redis-server /path/to/redis.conf
_._
_.-``__ ''-._
_.-`` `. `_. ''-._ Redis 5.0.7 (00000000/0) 64 bit
.-`` .-```. ```\/ _.,_ ''-._
( ' , .-` | `, ) Running in standalone mode
|`-._`-...-` __...-.``-._|'` _.-'| Port: 6379
| `-._ `._ / _.-' | PID: 687
`-._ `-._ `-./ _.-' _.-'
|`-._`-._ `-.__.-' _.-'_.-'|
| `-._`-._ _.-'_.-' | http://redis.io
`-._ `-._`-.__.-'_.-' _.-'
|`-._`-._ `-.__.-' _.-'_.-'|
| `-._`-._ _.-'_.-' |
`-._ `-._`-.__.-'_.-' _.-'
`-._ `-.__.-' _.-'
`-._ _.-'
`-.__.-'

687:M 24 Mar 2021 15:11:00.661 # WARNING: The TCP backlog setting of 511 cannot be enforced because /proc/sys/net/core/somaxconn is set to the lower value of 128.
687:M 24 Mar 2021 15:11:00.661 # Server initialized
687:M 24 Mar 2021 15:11:00.661 # WARNING overcommit_memory is set to 0! Background save may fail under low memory condition. To fix this issue add 'vm.overcommit_memory = 1' to /etc/sysctl.conf and then reboot or run the command 'sysctl vm.overcommit_memory=1' for this to take effect.
687:M 24 Mar 2021 15:11:00.662 * DB loaded from disk: 0.001 seconds
687:M 24 Mar 2021 15:11:00.662 * Ready to accept connections

[grape_ll]

ポート番号については，どのようにすれば6379以外で行っているかを確認することが出来ますでしょうか

[退会済みユーザー]

端末をもう一つ開くか、redis-server & としてバックグラウンドで実行すれば良いでしょう。ポート番号は何もしなくても6379で正しい番号になっています。

[grape_ll]

私はVScode上で行っているのですが，もう一つ端末を開くとは，VScodeのタブを二つにして行うということでしょうか．