127.0.0.1 or localhost?

[CTXMedia]

When a machine refers to itself in config files etc. is it better to use the IP address (127.0.0.1) or DNS name (localhost)?

ISTR reading somewhere that the IP address was the most efficient because it removed the need for a name lookup/resolution, but I'm not convinved that local host does a lookup?

Anyone know - or are they the same?

Cheers,
Shaun

 

[Slavik]

127.0.0.1 will be faster, though the localhost lookup will be a few ms at most.

 

[MattW]

127.0.0.1 won't do a lookup in your /etc/hosts file, but that will probably be really small anyway, so you'll not really notice any difference.

[root@vps2 elasticsearch]#cat /etc/hosts
127.0.0.1              localhost.localdomain localhost
xxx.xxx.xxx.xxx                    vps2.z22se.com

 

[MattW]

Also, won't localhost try to connect to a unix socket in the first instance?

 

[Mike]

Also, won't localhost try to connect to a unix socket in the first instance?

Yeah, I was going to comment on that.

 

[CTXMedia]

Also, won't localhost try to connect to a unix socket in the first instance?

Is that a good or a bad thing? And would it be required in some instances?

 

[MattW]

unix socket supposed to be faster than tcp/ip, because it doesn't have the tcp/ip overhead. It's also secure for stuff like MySQL where you can only connect to it on the local machine.

 

[CTXMedia]

unix socket supposed to be faster than tcp/ip, because it doesn't have the tcp/ip overhead. It's also secure for stuff like MySQL where you can only connect to it on the local machine.

So for my XF config.php file I want to be using 'localhost' as opposed to 127.0.0.1 ?

 

[MattW]

So for my XF config.php file I want to be using 'localhost' as opposed to 127.0.0.1 ?

Yeah, then it will connect to the socket for MySQL, as opposed to tcp port 3306.

Do a netstat -an | grep 3306 is see if you currently have any connections to MySQL on that port.

I have skip-networking enabled in MySQL, so it doesn't even port a listen on that port

root@vps [/home/z22se/public_html/forum/library]# netstat -an | grep 3306
root@vps [/home/z22se/public_html/forum/library]#

 

[CTXMedia]

root:/# netstat -an | grep 3306
tcp        0      0 0.0.0.0:3306            0.0.0.0:*               LISTEN

Presumably it would be better to use localhost for my backend cache server name instead of 127.0.0.1 too?

 

[MattW]

root:/# netstat -an | grep 3306
tcp        0      0 0.0.0.0:3306            0.0.0.0:*              LISTEN

Presumably it would be better to use localhost for my backend cache server name instead of 127.0.0.1 too?

What do you use for the back end cache?

 

[Adam Howard]

So for my XF config.php file I want to be using 'localhost' as opposed to 127.0.0.1 ?

I'm going to argue that it varies depending on setup. I had one host where 127.0.01 was fast and others where localhost was faster.

Of course these were in shared hosting setups, so I'm sure there were other factors.

 

[CTXMedia]

Libmemcached backend on Debian dedicated server with Percona MySQL.

 

[Deebs]

These types of threads urge me to kill things.

 

[MattW]

These types of threads urge me to kill things.

Care to expand?

 

[Deebs]

Sure. Localhost or 127.0.0.1 on the same box will be sub nanoseconds. It is the same box.

 

[MattW]

Sure. Localhost or 127.0.0.1 on the same box will be sub nanoseconds. It is the same box.

True, but that's not the only thing that has been discussed in this thread.

 

[CTXMedia]

Sure. Localhost or 127.0.0.1 on the same box will be sub nanoseconds. It is the same box.

Well I personally don't need to save time - I have a 64GB RAM SSD server that coasts even at busy times - but I was interested in the difference and whether using one or the other was faster / a better convention / or made a practical or programatic difference?

If there's a good practical reason for using localhost then that's what I'd like to do; but if there's absolutely no difference that's good to know too.

Cheers,
Shaun

 

[MattW]

Libmemcached backend on Debian dedicated server with Percona MySQL.

You'd have to configure Memcached to listen on a unix socket, rather than port 11211

http://xenforo.com/community/resources/micro-optimization-run-memcached-from-a-socket.1597/

 

[Deebs]

Sysadmins will use localhost. It will resolve to their local box where the command was run.