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Subject: Re: [OMPI users] MPI::Intracomm::Spawn and cluster configuration
From: Ralph Castain (rhc_at_[hidden])
Date: 2012-08-22 10:15:44


Sure, that's still true on all 1.3 or above releases. All you need to do is set the hostfile envar so we pick it up:

OMPI_MCA_orte_default_hostfile=<foo>

On Aug 21, 2012, at 7:23 PM, Brian Budge <brian.budge_at_[hidden]> wrote:

> Hi. I know this is an old thread, but I'm curious if there are any
> tutorials describing how to set this up? Is this still available on
> newer open mpi versions?
>
> Thanks,
> Brian
>
> On Fri, Jan 4, 2008 at 7:57 AM, Ralph Castain <rhc_at_[hidden]> wrote:
>> Hi Elena
>>
>> I'm copying this to the user list just to correct a mis-statement on my part
>> in an earlier message that went there. I had stated that a singleton could
>> comm_spawn onto other nodes listed in a hostfile by setting an environmental
>> variable that pointed us to the hostfile.
>>
>> This is incorrect in the 1.2 code series. That series does not allow
>> singletons to read a hostfile at all. Hence, any comm_spawn done by a
>> singleton can only launch child processes on the singleton's local host.
>>
>> This situation has been corrected for the upcoming 1.3 code series. For the
>> 1.2 series, though, you will have to do it via an mpirun command line.
>>
>> Sorry for the confusion - I sometimes have too many code families to keep
>> straight in this old mind!
>>
>> Ralph
>>
>>
>> On 1/4/08 5:10 AM, "Elena Zhebel" <ezhebel_at_[hidden]> wrote:
>>
>>> Hello Ralph,
>>>
>>> Thank you very much for the explanations.
>>> But I still do not get it running...
>>>
>>> For the case
>>> mpirun -n 1 -hostfile my_hostfile -host my_master_host my_master.exe
>>> everything works.
>>>
>>> For the case
>>> ./my_master.exe
>>> it does not.
>>>
>>> I did:
>>> - create my_hostfile and put it in the $HOME/.openmpi/components/
>>> my_hostfile :
>>> bollenstreek slots=2 max_slots=3
>>> octocore01 slots=8 max_slots=8
>>> octocore02 slots=8 max_slots=8
>>> clstr000 slots=2 max_slots=3
>>> clstr001 slots=2 max_slots=3
>>> clstr002 slots=2 max_slots=3
>>> clstr003 slots=2 max_slots=3
>>> clstr004 slots=2 max_slots=3
>>> clstr005 slots=2 max_slots=3
>>> clstr006 slots=2 max_slots=3
>>> clstr007 slots=2 max_slots=3
>>> - setenv OMPI_MCA_rds_hostfile_path my_hostfile (I put it in .tcshrc and
>>> then source .tcshrc)
>>> - in my_master.cpp I did
>>> MPI_Info info1;
>>> MPI_Info_create(&info1);
>>> char* hostname =
>>> "clstr002,clstr003,clstr005,clstr006,clstr007,octocore01,octocore02";
>>> MPI_Info_set(info1, "host", hostname);
>>>
>>> _intercomm = intracomm.Spawn("./childexe", argv1, _nProc, info1, 0,
>>> MPI_ERRCODES_IGNORE);
>>>
>>> - After I call the executable, I've got this error message
>>>
>>> bollenstreek: > ./my_master
>>> number of processes to run: 1
>>> --------------------------------------------------------------------------
>>> Some of the requested hosts are not included in the current allocation for
>>> the application:
>>> ./childexe
>>> The requested hosts were:
>>> clstr002,clstr003,clstr005,clstr006,clstr007,octocore01,octocore02
>>>
>>> Verify that you have mapped the allocated resources properly using the
>>> --host specification.
>>> --------------------------------------------------------------------------
>>> [bollenstreek:21443] [0,0,0] ORTE_ERROR_LOG: Out of resource in file
>>> base/rmaps_base_support_fns.c at line 225
>>> [bollenstreek:21443] [0,0,0] ORTE_ERROR_LOG: Out of resource in file
>>> rmaps_rr.c at line 478
>>> [bollenstreek:21443] [0,0,0] ORTE_ERROR_LOG: Out of resource in file
>>> base/rmaps_base_map_job.c at line 210
>>> [bollenstreek:21443] [0,0,0] ORTE_ERROR_LOG: Out of resource in file
>>> rmgr_urm.c at line 372
>>> [bollenstreek:21443] [0,0,0] ORTE_ERROR_LOG: Out of resource in file
>>> communicator/comm_dyn.c at line 608
>>>
>>> Did I miss something?
>>> Thanks for help!
>>>
>>> Elena
>>>
>>>
>>> -----Original Message-----
>>> From: Ralph H Castain [mailto:rhc_at_[hidden]]
>>> Sent: Tuesday, December 18, 2007 3:50 PM
>>> To: Elena Zhebel; Open MPI Users <users_at_[hidden]>
>>> Cc: Ralph H Castain
>>> Subject: Re: [OMPI users] MPI::Intracomm::Spawn and cluster configuration
>>>
>>>
>>>
>>>
>>> On 12/18/07 7:35 AM, "Elena Zhebel" <ezhebel_at_[hidden]> wrote:
>>>
>>>> Thanks a lot! Now it works!
>>>> The solution is to use mpirun -n 1 -hostfile my.hosts *.exe and pass
>>> MPI_Info
>>>> Key to the Spawn function!
>>>>
>>>> One more question: is it necessary to start my "master" program with
>>>> mpirun -n 1 -hostfile my_hostfile -host my_master_host my_master.exe ?
>>>
>>> No, it isn't necessary - assuming that my_master_host is the first host
>>> listed in your hostfile! If you are only executing one my_master.exe (i.e.,
>>> you gave -n 1 to mpirun), then we will automatically map that process onto
>>> the first host in your hostfile.
>>>
>>> If you want my_master.exe to go on someone other than the first host in the
>>> file, then you have to give us the -host option.
>>>
>>>>
>>>> Are there other possibilities for easy start?
>>>> I would say just to run ./my_master.exe , but then the master process
>>> doesn't
>>>> know about the available in the network hosts.
>>>
>>> You can set the hostfile parameter in your environment instead of on the
>>> command line. Just set OMPI_MCA_rds_hostfile_path = my.hosts.
>>>
>>> You can then just run ./my_master.exe on the host where you want the master
>>> to reside - everything should work the same.
>>>
>>> Just as an FYI: the name of that environmental variable is going to change
>>> in the 1.3 release, but everything will still work the same.
>>>
>>> Hope that helps
>>> Ralph
>>>
>>>
>>>>
>>>> Thanks and regards,
>>>> Elena
>>>>
>>>>
>>>> -----Original Message-----
>>>> From: Ralph H Castain [mailto:rhc_at_[hidden]]
>>>> Sent: Monday, December 17, 2007 5:49 PM
>>>> To: Open MPI Users <users_at_[hidden]>; Elena Zhebel
>>>> Cc: Ralph H Castain
>>>> Subject: Re: [OMPI users] MPI::Intracomm::Spawn and cluster configuration
>>>>
>>>>
>>>>
>>>>
>>>> On 12/17/07 8:19 AM, "Elena Zhebel" <ezhebel_at_[hidden]> wrote:
>>>>
>>>>> Hello Ralph,
>>>>>
>>>>> Thank you for your answer.
>>>>>
>>>>> I'm using OpenMPI 1.2.3. , compiler glibc232, Linux Suse 10.0.
>>>>> My "master" executable runs only on the one local host, then it spawns
>>>>> "slaves" (with MPI::Intracomm::Spawn).
>>>>> My question was: how to determine the hosts where these "slaves" will be
>>>>> spawned?
>>>>> You said: "You have to specify all of the hosts that can be used by
>>>>> your job
>>>>> in the original hostfile". How can I specify the host file? I can not
>>>>> find it
>>>>> in the documentation.
>>>>
>>>> Hmmm...sorry about the lack of documentation. I always assumed that the MPI
>>>> folks in the project would document such things since it has little to do
>>>> with the underlying run-time, but I guess that fell through the cracks.
>>>>
>>>> There are two parts to your question:
>>>>
>>>> 1. how to specify the hosts to be used for the entire job. I believe that
>>> is
>>>> somewhat covered here:
>>>> http://www.open-mpi.org/faq/?category=running#simple-spmd-run
>>>>
>>>> That FAQ tells you what a hostfile should look like, though you may already
>>>> know that. Basically, we require that you list -all- of the nodes that both
>>>> your master and slave programs will use.
>>>>
>>>> 2. how to specify which nodes are available for the master, and which for
>>>> the slave.
>>>>
>>>> You would specify the host for your master on the mpirun command line with
>>>> something like:
>>>>
>>>> mpirun -n 1 -hostfile my_hostfile -host my_master_host my_master.exe
>>>>
>>>> This directs Open MPI to map that specified executable on the specified
>>> host
>>>> - note that my_master_host must have been in my_hostfile.
>>>>
>>>> Inside your master, you would create an MPI_Info key "host" that has a
>>> value
>>>> consisting of a string "host1,host2,host3" identifying the hosts you want
>>>> your slave to execute upon. Those hosts must have been included in
>>>> my_hostfile. Include that key in the MPI_Info array passed to your Spawn.
>>>>
>>>> We don't currently support providing a hostfile for the slaves (as opposed
>>>> to the host-at-a-time string above). This may become available in a future
>>>> release - TBD.
>>>>
>>>> Hope that helps
>>>> Ralph
>>>>
>>>>>
>>>>> Thanks and regards,
>>>>> Elena
>>>>>
>>>>> -----Original Message-----
>>>>> From: users-bounces_at_[hidden] [mailto:users-bounces_at_[hidden]] On
>>>>> Behalf Of Ralph H Castain
>>>>> Sent: Monday, December 17, 2007 3:31 PM
>>>>> To: Open MPI Users <users_at_[hidden]>
>>>>> Cc: Ralph H Castain
>>>>> Subject: Re: [OMPI users] MPI::Intracomm::Spawn and cluster
>>>>> configuration
>>>>>
>>>>> On 12/12/07 5:46 AM, "Elena Zhebel" <ezhebel_at_[hidden]> wrote:
>>>>>>
>>>>>>
>>>>>> Hello,
>>>>>>
>>>>>> I'm working on a MPI application where I'm using OpenMPI instead of
>>>>>> MPICH.
>>>>>>
>>>>>> In my "master" program I call the function MPI::Intracomm::Spawn which
>>>>> spawns
>>>>>> "slave" processes. It is not clear for me how to spawn the "slave"
>>>>> processes
>>>>>> over the network. Currently "master" creates "slaves" on the same
>>>>>> host.
>>>>>>
>>>>>> If I use 'mpirun --hostfile openmpi.hosts' then processes are spawn
>>>>>> over
>>>>> the
>>>>>> network as expected. But now I need to spawn processes over the
>>>>>> network
>>>>> from
>>>>>> my own executable using MPI::Intracomm::Spawn, how can I achieve it?
>>>>>>
>>>>>
>>>>> I'm not sure from your description exactly what you are trying to do,
>>>>> nor in
>>>>> what environment this is all operating within or what version of Open
>>>>> MPI
>>>>> you are using. Setting aside the environment and version issue, I'm
>>>>> guessing
>>>>> that you are running your executable over some specified set of hosts,
>>>>> but
>>>>> want to provide a different hostfile that specifies the hosts to be
>>>>> used for
>>>>> the "slave" processes. Correct?
>>>>>
>>>>> If that is correct, then I'm afraid you can't do that in any version
>>>>> of Open
>>>>> MPI today. You have to specify all of the hosts that can be used by
>>>>> your job
>>>>> in the original hostfile. You can then specify a subset of those hosts
>>>>> to be
>>>>> used by your original "master" program, and then specify a different
>>>>> subset
>>>>> to be used by the "slaves" when calling Spawn.
>>>>>
>>>>> But the system requires that you tell it -all- of the hosts that are
>>>>> going
>>>>> to be used at the beginning of the job.
>>>>>
>>>>> At the moment, there is no plan to remove that requirement, though
>>>>> there has
>>>>> been occasional discussion about doing so at some point in the future.
>>>>> No
>>>>> promises that it will happen, though - managed environments, in
>>>>> particular,
>>>>> currently object to the idea of changing the allocation on-the-fly. We
>>>>> may,
>>>>> though, make a provision for purely hostfile-based environments (i.e.,
>>>>> unmanaged) at some time in the future.
>>>>>
>>>>> Ralph
>>>>>
>>>>>>
>>>>>>
>>>>>> Thanks in advance for any help.
>>>>>>
>>>>>> Elena
>>>>>>
>>>>>>
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>>>>>
>>>>>
>>>>>
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>>>
>>>
>>
>>
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