Error when starting Redis server: "Address already in use"

I had this same problems, but I forgot that redis persists. If you get this error, try this command:

redis-cli ping

And this solved my issue:

[root@tannetto tannetto]# ps -ef |grep redis
root      4871  4836  0 11:07 pts/0    00:00:00 grep redis
redis     4995     1  0 Jun23 ?        04:21:50 /usr/bin/redis-server *:6379

After finding redis, kill -9 it!

[root@tannetto tannetto]# kill -9 4995
[root@tannetto tannetto]# service redis restart
Stopping redis-server:                                     [  OK  ]
Starting redis-server:                                     [  OK  ]
[root@tannetto tannetto]# service redis status
redis-server (pid  4919) is running...