Redis错误8：连接localhost:6379时，未提供节点名或服务名，或未知

Question

我的环境是 Mac OS 10.9.2，使用的是 python3.3 和 redis-2.6.9（64位）。

我有很多线程（差不多 2000 个）同时使用同一个 redis 实例来写数据，但有些线程出现了以下异常：

During handling of the above exception, another exception occurred:

Traceback (most recent call last):
  File "/usr/local/lib/python3.3/site-packages/redis/connection.py", line 250, in connect
    sock = self._connect()
  File "/usr/local/lib/python3.3/site-packages/redis/connection.py", line 268, in _connect
    self.socket_timeout)
  File "/usr/local/Cellar/python3/3.3.4/Frameworks/Python.framework/Versions/3.3/lib/python3.3/socket.py", line 417, in create_connecti
on
    for res in getaddrinfo(host, port, 0, SOCK_STREAM):
socket.gaierror: [Errno 8] nodename nor servname provided, or not known

Traceback (most recent call last):
  File "/usr/local/Cellar/python3/3.3.4/Frameworks/Python.framework/Versions/3.3/lib/python3.3/threading.py", line 901, in _bootstrap_i
nner
    self.run()
  File "/usr/local/Cellar/python3/3.3.4/Frameworks/Python.framework/Versions/3.3/lib/python3.3/threading.py", line 858, in run
    self._target(*self._args, **self._kwargs)
  File "proxypool.py", line 289, in _efficiency_proxy
    self.rdb.zadd(db_proxy, time_delay, proxy)
  File "/usr/local/lib/python3.3/site-packages/redis/client.py", line 1345, in zadd
    return self.execute_command('ZADD', name, *pieces)
  File "/usr/local/lib/python3.3/site-packages/redis/client.py", line 464, in execute_command
    connection.send_command(*args)
  File "/usr/local/lib/python3.3/site-packages/redis/connection.py", line 334, in send_command
    self.send_packed_command(self.pack_command(*args))
  File "/usr/local/lib/python3.3/site-packages/redis/connection.py", line 316, in send_packed_command
    self.connect()
  File "/usr/local/lib/python3.3/site-packages/redis/connection.py", line 253, in connect
    raise ConnectionError(self._error_message(e))
redis.exceptions.ConnectionError: Error 8 connecting localhost:6379. nodename nor servname provided, or not known.

有没有什么办法可以解决这个问题呢？
我尝试在出现这个异常时连接到 redis 服务器，并使用 ulimit -n 来设置一个更大的数字，但这两种方法都没有效果。

Answer 1

我也遇到过这个问题。

当你使用了错误的 Redis 主机地址时，就会出现这个错误。

Answer 2

很可能是红色服务器没有在运行。你可以用“redis-server”这个命令来启动它。

brew services start redis (on mac)

Answer 3

我知道为什么会发生这个问题。这是因为连接到redis服务器的最大连接数受到了操作系统设置的最大文件处理器数量的限制。
如果我设置：

$ ulimit -n 1024

这样就可以正常工作了。