I confess I am sorely puzzled. I replace the Info key with MPI_INFO_NULL,
but still had to pass a bogus argument to master since you still have the
Info_set code in there - otherwise, info_set segfaults due to a NULL
argv[1]. Doing that (and replacing "hostname" with an MPI example code)
makes everything work just fine.
I've attached one of our example comm_spawn codes that we test against - it
also works fine with the current head of the 1.8 code base. I confess that
some changes have been made since 1.8.4 was released, and it is entirely
possible that this was a problem in 1.8.4 and has since been fixed.
So I'd suggest trying with the nightly 1.8 tarball and seeing if it works
for you. You can download it from here:
http://www.open-mpi.org/nightly/v1.8/
HTH
Ralph
On Tue, Feb 3, 2015 at 6:20 PM, Evan Samanas <evan.sama...@gmail.com> wrote:
> Yes, I did. I replaced the info argument of MPI_Comm_spawn with
> MPI_INFO_NULL.
>
> On Tue, Feb 3, 2015 at 5:54 PM, Ralph Castain <r...@open-mpi.org> wrote:
>
>> When running your comm_spawn code, did you remove the Info key code? You
>> wouldn't need to provide a hostfile or hosts any more, which is why it
>> should resolve that problem.
>>
>> I agree that providing either hostfile or host as an Info key will cause
>> the program to segfault - I'm woking on that issue.
>>
>>
>> On Tue, Feb 3, 2015 at 3:46 PM, Evan Samanas <evan.sama...@gmail.com>
>> wrote:
>>
>>> Setting these environment variables did indeed change the way mpirun
>>> maps things, and I didn't have to specify a hostfile. However, setting
>>> these for my MPI_Comm_spawn code still resulted in the same segmentation
>>> fault.
>>>
>>> Evan
>>>
>>> On Tue, Feb 3, 2015 at 10:09 AM, Ralph Castain <r...@open-mpi.org> wrote:
>>>
>>>> If you add the following to your environment, you should run on
>>>> multiple nodes:
>>>>
>>>> OMPI_MCA_rmaps_base_mapping_policy=node
>>>> OMPI_MCA_orte_default_hostfile=<your hostfile>
>>>>
>>>> The first tells OMPI to map-by node. The second passes in your default
>>>> hostfile so you don't need to specify it as an Info key.
>>>>
>>>> HTH
>>>> Ralph
>>>>
>>>>
>>>> On Tue, Feb 3, 2015 at 9:23 AM, Evan Samanas <evan.sama...@gmail.com>
>>>> wrote:
>>>>
>>>>> Hi Ralph,
>>>>>
>>>>> Good to know you've reproduced it. I was experiencing this using both
>>>>> the hostfile and host key. A simple comm_spawn was working for me as
>>>>> well,
>>>>> but it was only launching locally, and I'm pretty sure each node only has
>>>>> 4
>>>>> slots given past behavior (the mpirun -np 8 example I gave in my first
>>>>> email launches on both hosts). Is there a way to specify the hosts I want
>>>>> to launch on without the hostfile or host key so I can test remote launch?
>>>>>
>>>>> And to the "hostname" response...no wonder it was hanging! I just
>>>>> constructed that as a basic example. In my real use I'm launching
>>>>> something that calls MPI_Init.
>>>>>
>>>>> Evan
>>>>>
>>>>>
>>>>>
>>>>> _______________________________________________
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>>>>> Link to this post:
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>>>>>
>>>>
>>>>
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>>>>
>>>
>>>
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>>
>>
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>
>
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> users mailing list
> us...@open-mpi.org
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> Link to this post:
> http://www.open-mpi.org/community/lists/users/2015/02/26286.php
>
#include <stdio.h>
#include <sys/types.h>
#include <unistd.h>
#include <mpi.h>
int main(int argc, char* argv[])
{
int msg, rc;
MPI_Comm parent, child;
int rank, size;
char hostname[512];
pid_t pid;
pid = getpid();
printf("[pid %ld] starting up!\n", (long)pid);
MPI_Init(NULL, NULL);
MPI_Comm_rank(MPI_COMM_WORLD, &rank);
printf("%d completed MPI_Init\n", rank);
MPI_Comm_size(MPI_COMM_WORLD, &size);
MPI_Comm_get_parent(&parent);
/* If we get COMM_NULL back, then we're the parent */
if (MPI_COMM_NULL == parent) {
pid = getpid();
printf("Parent [pid %ld] about to spawn!\n", (long)pid);
if (MPI_SUCCESS != (rc = MPI_Comm_spawn(argv[0], MPI_ARGV_NULL, 3, MPI_INFO_NULL,
0, MPI_COMM_WORLD, &child, MPI_ERRCODES_IGNORE))) {
printf("Child failed to spawn\n");
return rc;
}
printf("Parent done with spawn\n");
if (0 == rank) {
msg = 38;
printf("Parent sending message to child\n");
MPI_Send(&msg, 1, MPI_INT, 0, 1, child);
}
MPI_Comm_disconnect(&child);
printf("Parent disconnected\n");
}
/* Otherwise, we're the child */
else {
MPI_Comm_rank(MPI_COMM_WORLD, &rank);
MPI_Comm_size(MPI_COMM_WORLD, &size);
gethostname(hostname, 512);
pid = getpid();
printf("Hello from the child %d of %d on host %s pid %ld\n", rank, 3, hostname, (long)pid);
if (0 == rank) {
MPI_Recv(&msg, 1, MPI_INT, 0, 1, parent, MPI_STATUS_IGNORE);
printf("Child %d received msg: %d\n", rank, msg);
}
MPI_Comm_disconnect(&parent);
printf("Child %d disconnected\n", rank);
}
MPI_Finalize();
fprintf(stderr, "%d: exiting\n", pid);
return 0;
}
