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Subject: Re: [OMPI users] MPI::Intracomm::Spawn and cluster configuration
From: Ralph Castain (rhc_at_[hidden])
Date: 2012-08-28 17:36:50


Hmmm...what is in your "hostsfile"?

On Aug 28, 2012, at 2:33 PM, Brian Budge <brian.budge_at_[hidden]> wrote:

> Hi Ralph -
>
> Thanks for confirming this is possible. I'm trying this and currently
> failing. Perhaps there's something I'm missing in the code to make
> this work. Here are the two instantiations and their outputs:
>
>> LD_LIBRARY_PATH=/home/budgeb/p4/pseb/external/lib.dev:/usr/local/lib OMPI_MCA_orte_default_hostfile=`pwd`/hostsfile ./master_exe
> cannot start slaves... not enough nodes
>
>> LD_LIBRARY_PATH=/home/budgeb/p4/pseb/external/lib.dev:/usr/local/lib OMPI_MCA_orte_default_hostfile=`pwd`/hostsfile mpirun -n 1 ./master_exe
> master spawned 1 slaves...
> slave responding...
>
>
> The code:
>
> //master.cpp
> #include <mpi.h>
> #include <boost/filesystem.hpp>
> #include <iostream>
>
> int main(int argc, char **args) {
> int worldSize, universeSize, *puniverseSize, flag;
>
> MPI_Comm everyone; //intercomm
> boost::filesystem::path curPath =
> boost::filesystem::absolute(boost::filesystem::current_path());
>
> std::string toRun = (curPath / "slave_exe").string();
>
> int ret = MPI_Init(&argc, &args);
>
> if(ret != MPI_SUCCESS) {
> std::cerr << "failed init" << std::endl;
> return -1;
> }
>
> MPI_Comm_size(MPI_COMM_WORLD, &worldSize);
>
> if(worldSize != 1) {
> std::cerr << "too many masters" << std::endl;
> }
>
> MPI_Attr_get(MPI_COMM_WORLD, MPI_UNIVERSE_SIZE, &puniverseSize, &flag);
>
> if(!flag) {
> std::cerr << "no universe size" << std::endl;
> return -1;
> }
> universeSize = *puniverseSize;
> if(universeSize == 1) {
> std::cerr << "cannot start slaves... not enough nodes" << std::endl;
> }
>
>
> char *buf = (char*)alloca(toRun.size() + 1);
> memcpy(buf, toRun.c_str(), toRun.size());
> buf[toRun.size()] = '\0';
>
> MPI_Comm_spawn(buf, MPI_ARGV_NULL, universeSize-1, MPI_INFO_NULL,
> 0, MPI_COMM_SELF, &everyone,
> MPI_ERRCODES_IGNORE);
>
> std::cerr << "master spawned " << universeSize-1 << " slaves..."
> << std::endl;
>
> MPI_Finalize();
>
> return 0;
> }
>
>
> //slave.cpp
> #include <mpi.h>
>
> int main(int argc, char **args) {
> int size;
> MPI_Comm parent;
> MPI_Init(&argc, &args);
>
> MPI_Comm_get_parent(&parent);
>
> if(parent == MPI_COMM_NULL) {
> std::cerr << "slave has no parent" << std::endl;
> }
> MPI_Comm_remote_size(parent, &size);
> if(size != 1) {
> std::cerr << "parent size is " << size << std::endl;
> }
>
> std::cerr << "slave responding..." << std::endl;
>
> MPI_Finalize();
>
> return 0;
> }
>
>
> Any ideas? Thanks for any help.
>
> Brian
>
> On Wed, Aug 22, 2012 at 9:03 AM, Ralph Castain <rhc_at_[hidden]> wrote:
>> 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
>>>>>>>>>>
>>>>>>>>>>
>>>>>>>>>> _______________________________________________
>>>>>>>>>> users mailing list
>>>>>>>>>> users_at_[hidden]
>>>>>>>>>> http://www.open-mpi.org/mailman/listinfo.cgi/users
>>>>>>>>>
>>>>>>>>>
>>>>>>>>>
>>>>>>>>> _______________________________________________
>>>>>>>>> users mailing list
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>>>>>>>>> http://www.open-mpi.org/mailman/listinfo.cgi/users
>>>>>>>>>
>>>>>>>>> _______________________________________________
>>>>>>>>> users mailing list
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>>>>>>>>
>>>>>>>>
>>>>>>>
>>>>>>>
>>>>>>
>>>>>>
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