Can you get on one of the nodes and see the job's processes?  If so can you then attach a debugger to it and get a stack?  I wonder if the processes are stuck in MPI_Init?


On 6/7/2012 6:06 AM, Duke wrote:
Hi again,

Somehow the verbose flag (-v) did not work for me. I tried --debug-daemon and got:

[mpiuser@fantomfs40a ~]$ mpirun --debug-daemons -np 3 --machinefile /home/mpiuser/.mpi_hostfile ./test/mpihello
Daemon was launched on hp430a - beginning to initialize
Daemon [[34432,0],1] checking in as pid 3011 on host hp430a
<stuck here>

Somehow the program got stuck when checking on hosts. The secure log on hp430a showed that mpiuser logged in just fine:

tail /var/log/secure
Jun  7 17:07:31 hp430a sshd[3007]: Accepted publickey for mpiuser from port 34037 ssh2
Jun  7 17:07:31 hp430a sshd[3007]: pam_unix(sshd:session): session opened for user mpiuser by (uid=0)

Any idea where/how/what to process/check?



On 6/7/12 4:38 PM, Duke wrote:
Hi Jingha,

On 6/7/12 4:28 PM, Jingcha Joba wrote:
Hello Duke,
Welcome to the forum.
The way openmpi schedules by default is to fill all the slots in a host, before moving on to next host.
Check this link for some info:

Thanks for quick answer. I checked the FAQ, and tried with processes more than 2, but somehow it got stalled:

[mpiuser@fantomfs40a ~]$ mpirun -v -np 4 --machinefile /home/mpiuser/.mpi_hostfile ./test/mpihello
^Cmpirun: killing job...

I tried --host flag and it got stalled as well:

[mpiuser@fantomfs40a ~]$ mpirun -v -np 4 --host hp430a,hp430b ./test/mpihello

My configuration must be wrong somewhere. Anyidea how I can check the system?




On Thu, Jun 7, 2012 at 2:11 AM, Duke <> wrote:
Hi folks,

Please be gentle to the newest member of openMPI, I am totally new to this field. I just built a test cluster with 3 boxes on Scientific Linux 6.2 and openMPI (Open MPI 1.5.3), and I wanted to test how the cluster works but I cant figure out what was/is happening. On my master node, I have the hostfile:

[mpiuser@fantomfs40a ~]$ cat .mpi_hostfile
# The Hostfile for Open MPI
fantomfs40a slots=2
hp430a slots=4 max-slots=4
hp430b slots=4 max-slots=4

To test, I used the following c code:

[mpiuser@fantomfs40a ~]$ cat test/mpihello.c
/* program hello */
/* Adapted from mpihello.f by drs */

#include <mpi.h>
#include <stdio.h>

int main(int argc, char **argv)
 int *buf, i, rank, nints, len;
 char hostname[256];

 MPI_Comm_rank(MPI_COMM_WORLD, &rank);
 printf("Hello world!  I am process number: %d on host %s\n", rank, hostname);
 return 0;

and then compiled and ran:

[mpiuser@fantomfs40a ~]$ mpicc -o test/mpihello test/mpihello.c
[mpiuser@fantomfs40a ~]$ mpirun -np 2 --machinefile /home/mpiuser/.mpi_hostfile ./test/mpihello
Hello world!  I am process number: 0 on host fantomfs40a
Hello world!  I am process number: 1 on host fantomfs40a

Unfortunately the result did not show what I wanted. I expected to see somethign like:

Hello world!  I am process number: 0 on host hp430a
Hello world!  I am process number: 1 on host hp430b

Anybody has any idea what I am doing wrong?

Thank you in advance,


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