[MPICH] DHCP assigned IP addresses and hostnames?

[Ralph Butler]

I do not think these changes should be necessary.   But, I must confess
that I no longer believe that I understand  what problem you are  
trying to solve.  Also, using mpdboot
should work just fine, but is merely an extra step if you are running  
on a single host.

On FriNov 17, at Fri Nov 17 2:52PM, Steve Kargl wrote:

> On Thu, Nov 16, 2006 at 01:04:42PM -0800, Steve Kargl wrote:
>> On Thu, Nov 16, 2006 at 02:32:35PM -0600, Ralph Butler wrote:
>>> On ThuNov 16, at Thu Nov 16 1:32PM, Steve Kargl wrote:
>>>> I've set up mpich2 on a colleagues duo-core opteron laptop
>>>> so that he can do some development before moving to the
>>>> cluster.  His laptop gets an IP address assigned by DHCP
>>>> and his hostname is not a fully qualified domain name.
>>>>
>>>> I can tell him to update mpd.hosts with the current IP
>>>> address upon each reboot, but I haven't found a way to
>>>> get around this:
>>>>
>>>> alien-mobile:fcurra[203] mpdboot
>>>> mpdboot_alien-mobile.apl.washington.edu (handle_mpd_output 388):
>>>> from mpd on alien-mobile.apl.washington.edu, invalid port info:
>>>> mpd failed: gethostbyname_ex failed for alien-
>>>> mobile.apl.washington.edu
>>>>
>>>> Is there some way to tell MPICH2 to use localhost and the 127.0.0.1
>>>> address?
>>>>
>>>
>>> I believe the following demos what you want.
>>> --ralph
>>>
>>> (rmbmac:78) % mpd --ifhn=127.0.0.1 &
>>> [1] 26620
>>> (rmbmac:79) % mpdtrace  -l
>>> rmbmac.cs.mtsu.edu_52052 (127.0.0.1)
>>> (rmbmac:80) % mpiexec  -n 1 hostname
>>> rmbmac.cs.mtsu.edu
>>
>> Thanks!  I thought I had tried explicit use of the 127.0.0.1
>> address, but apparently I missed this.
>>
>
> I spoke to soon.  In testing, I used hostname to change the
> fake name of the laptop to the fully qualified domain name
> associated with the IP address of the ethernet nic.  So, the
> "mpdboot  --ifhn=127.0.0.1" appeared to work.
>
> To get mpich2 to run on localhost, I had to hack up the
> following patch:
>
>
> --- mpdboot.orig	Wed Sep  6 13:33:29 2006
> +++ mpdboot	Fri Nov 17 12:36:06 2006
> @@ -65,7 +65,7 @@
>
>  def mpdboot():
>      global myHost, fullDirName, rshCmd, user, mpdCmd, debug, verbose
> -    myHost = gethostname()
> +    myHost = 'alien'
>      mpd_set_my_id('mpdboot_%s' % (myHost) )
>      fullDirName  = path.abspath(path.split(argv[0])[0])
>      rshCmd = 'ssh'
> --- mpd.py.orig	Fri Nov 17 12:37:08 2006
> +++ mpd.py	Fri Nov 17 12:41:06 2006
> @@ -108,7 +108,7 @@
>      def __init__(self):
>          self.myHost = socket.gethostname()
>          try:
> -            hostinfo = socket.gethostbyname_ex(self.myHost)
> +            hostinfo = '127.0.0.1' #socket.gethostbyname_ex 
> (self.myHost)
>              self.myIfhn = hostinfo[2][0]    # chgd below when I  
> get the real value
>          except:
>              print 'mpd failed: gethostbyname_ex failed for %s' %  
> (self.myHost)
> @@ -371,7 +371,7 @@
>                      print 'failed to parse --ifhn option'
>                      self.usage()
>                  try:
> -                    hostinfo = socket.gethostbyname_ex(ifhn)
> +                    hostinfo = '127.0.0.1' #socket.gethostbyname_ex 
> (ifhn)
>                      ifhn = hostinfo[2][0]
>                  except:
>                      print 'mpd failed: gethostbyname_ex failed for  
> %s' % (ifhn)
>
>
> I don't know python.  Otherwise, I would add a -localhost
> option to permit "mpdboot -localhost".
>
> Crude, my colleague just informed me that mpiexec is now dying with
> a gethostbyname_ex failure.
>
> -- 
> Steve