Ray start --head error,Unable to connect to Redis at

Can anyone help me solve this problem? Thanks

when use ray start --head

[root@ecs-0005 servers]# ray start --head
Local node IP:
Traceback (most recent call last):
File “/usr/local/lib/python3.7/site-packages/redis/connection.py”, line 576, in connect
sock = self._connect()
File “/usr/local/lib/python3.7/site-packages/redis/connection.py”, line 634, in _connect
raise err
File “/usr/local/lib/python3.7/site-packages/redis/connection.py”, line 622, in _connect
ConnectionRefusedError: [Errno 111] Connection refused

During handling of the above exception, another exception occurred:

Traceback (most recent call last):
File “/usr/local/lib/python3.7/site-packages/ray/_private/services.py”, line 648, in wait_for_redis_to_start
File “/usr/local/lib/python3.7/site-packages/redis/commands/core.py”, line 358, in client_list
return self.execute_command(‘CLIENT LIST’, *args)
File “/usr/local/lib/python3.7/site-packages/redis/client.py”, line 1085, in execute_command
conn = self.connection or pool.get_connection(command_name, **options)
File “/usr/local/lib/python3.7/site-packages/redis/connection.py”, line 1182, in get_connection
File “/usr/local/lib/python3.7/site-packages/redis/connection.py”, line 580, in connect
raise ConnectionError(self._error_message(e))
redis.exceptions.ConnectionError: Error 111 connecting to Connection refused.

The above exception was the direct cause of the following exception:

Traceback (most recent call last):
File “/usr/local/bin/ray”, line 8, in
File “/usr/local/lib/python3.7/site-packages/ray/scripts/scripts.py”, line 1969, in main
return cli()
File “/usr/local/lib/python3.7/site-packages/click/core.py”, line 1128, in call
return self.main(*args, **kwargs)
File “/usr/local/lib/python3.7/site-packages/click/core.py”, line 1053, in main
rv = self.invoke(ctx)
File “/usr/local/lib/python3.7/site-packages/click/core.py”, line 1659, in invoke
return _process_result(sub_ctx.command.invoke(sub_ctx))
File “/usr/local/lib/python3.7/site-packages/click/core.py”, line 1395, in invoke
return ctx.invoke(self.callback, **ctx.params)
File “/usr/local/lib/python3.7/site-packages/click/core.py”, line 754, in invoke
return __callback(*args, **kwargs)
File “/usr/local/lib/python3.7/site-packages/ray/scripts/scripts.py”, line 626, in start
ray_params, head=True, shutdown_at_exit=block, spawn_reaper=block)
File “/usr/local/lib/python3.7/site-packages/ray/node.py”, line 248, in init
File “/usr/local/lib/python3.7/site-packages/ray/node.py”, line 900, in start_head_processes
File “/usr/local/lib/python3.7/site-packages/ray/node.py”, line 720, in start_redis
File “/usr/local/lib/python3.7/site-packages/ray/_private/services.py”, line 875, in start_redis
listen_to_localhost_only=(node_ip_address == “”))
File “/usr/local/lib/python3.7/site-packages/ray/_private/services.py”, line 1030, in _start_redis_instance
wait_for_redis_to_start(“”, port, password=password)
File “/usr/local/lib/python3.7/site-packages/ray/_private/services.py”, line 670, in wait_for_redis_to_start
" attempts to ping the Redis server.") from connEx
RuntimeError: Unable to connect to Redis at after 16 retries. Check that is reachable from this machine. If it is not, your firewall may be blocking this port. If the problem is a flaky connection, try setting the environment variable RAY_START_REDIS_WAIT_RETRIES to increase the number of attempts to ping the Redis server.

It seems you didn’t perform ray.stop from the earlier attempts. I suggest, run netstat or ps -ef on this node and make sure no Redis process not running. If it is running then kill it and start ray again.

I believe you starting ray head with embedded Redis server and not remote Redis server.

Thank you for your answers, but I don’t seem to have started ray successfully. I feel that redis did not start successfully when ray was started, so redis could not be connected.

[root@ecs-0005 ~]# ps -aux|grep redis
root 188328 0.0 0.0 214016 1536 pts/0 S+ 11:51 0:00 grep redis

redis 4.0

Can you first try start ray from python interactive mode and see if it works

# python 
import ray

After that, you can start ray head (make sure to replace IP address if it is not the same)

ray start --head --node-ip-address= --address=

I suggest you to try ray official release 1.8.0 instead of ray-2-dev daily build.