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Subject: Re: [OMPI users] MPI::Intracomm::Spawn and cluster configuration
From: Ralph Castain (rhc_at_[hidden])
Date: 2012-08-22 12:03:27


It really is just that simple :-)

On Aug 22, 2012, at 8:56 AM, Brian Budge <brian.budge_at_[hidden]> wrote:

> Okay. Is there a tutorial or FAQ for setting everything up? Or is it
> really just that simple? I don't need to run a copy of the orte
> server somewhere?
>
> if my current ip is 192.168.0.1,
>
> 0 > echo 192.168.0.11 > /tmp/hostfile
> 1 > echo 192.168.0.12 >> /tmp/hostfile
> 2 > export OMPI_MCA_orte_default_hostfile=/tmp/hostfile
> 3 > ./mySpawningExe
>
> At this point, mySpawningExe will be the master, running on
> 192.168.0.1, and I can have spawned, for example, childExe on
> 192.168.0.11 and 192.168.0.12? Or childExe1 on 192.168.0.11 and
> childExe2 on 192.168.0.12?
>
> Thanks for the help.
>
> Brian
>
> On Wed, Aug 22, 2012 at 7:15 AM, Ralph Castain <rhc_at_[hidden]> wrote:
>> 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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