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Subject: Re: [OMPI users] Dynamic process tutorials?
From: Brian Budge (brian.budge_at_[hidden])
Date: 2010-07-12 13:12:29


HI Ralph -

Thanks for the reply. I think this patch sounds great! The idea in
our software is that it won't be known until after the program is
running whether or not MPI is needed, so it would be best if the
communication initialization could be done programmatically instead of
through an external program like mpirun. Is there a plan for this to
enter the mainline?

  Brian

On Mon, Jul 12, 2010 at 8:29 AM, Ralph Castain <rhc_at_[hidden]> wrote:
>
> On Jul 12, 2010, at 9:07 AM, Brian Budge wrote:
>
>> Hi Jody -
>>
>> Thanks for the reply.  is there a way of "fusing" intercommunicators?
>> Let's say I have a higher level node scheduler, and it makes a new
>> node available to a COMM that is already running.  So the master
>> spawns another process for that node.  How can the new process
>> communicate with the other already started processes?
>
> They can connect/accept via ompi-server - checkout "man ompi-server". You can also have them all rendezvous at a common mpirun if you prefer by using the appropriate mca param to give the required contact info.
>
>>
>> Also, how can you specify with MPI_Comm_spawn/multiple() how do you
>> specify IP addresses on which to start the processes?
>
> Look at "man MPI_Comm_spawn"
>
>>
>> If my higher level node scheduler needs to take away a process from my
>> COMM, is it good/bad for that node to call MPI_Finalize as it exits?
>
> The entire job will automatically abort if it fails to call Finalize as this is considered an abnormal termination event.
>
>>
>> I would prefer not to use any of the MPI command-line utilities
>> (mpirun/mpiexec) if that's possible.
>
> Not possible at the moment. I have provided a patch to another user on this list that made it possible to use ompi-server as a rendezvous point for singletons, but that isn't in any formal release yet.
>
>>
>> Thanks,
>>  Brian
>>
>> On Sat, Jul 10, 2010 at 11:53 PM, jody <jody.xha_at_[hidden]> wrote:
>>> Hi Brian
>>> When you spawn processes with MPI_Comm_spawn(), one of the arguments
>>> will be set to an intercommunicator of thes spawner and the spawnees.
>>> You can use this intercommunicator as the communicator argument
>>> in the MPI_functions.
>>>
>>> Jody
>>> On Fri, Jul 9, 2010 at 5:56 PM, Brian Budge <brian.budge_at_[hidden]> wrote:
>>>> Hi all -
>>>>
>>>> I've been looking at the dynamic process features of mpi-2.  I have managed
>>>> to actually launch processes using spawn, but haven't seen examples for
>>>> actually communicating once these processes are launched.  I am additionally
>>>> interested in how processes created through multiple spawn calls can
>>>> communicate.
>>>>
>>>> Does anyone know of resources that describe these topics?  My google-fu must
>>>> not be up to par :)
>>>>
>>>> Thanks,
>>>>   Brian
>>>>
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>>>>
>>>
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