Error with mpiexec: MPI_Comm_Size always 1!

Error with mpiexec: MPI_Comm_Size always 1!

I've followed the instructions in the 'getting started' file to set up a linux cluster with 4 nodes. Mpdboot works ok as mpdtrace verifies, and my programs compile, but don't run as they should: Taking the testc program as an example, with the command:

mpiexec -n 4 --machinefile ~/mpd.hosts ./testc

I get the output:
Hello world: rank 0 of 1 running on node1
Hello world: rank 0 of 1 running on node2
Hello world: rank 0 of 1 running on node3
Hello world: rank 0 of 1 running on node4

...so while the job is farmed out to the 4 nodes, each node thinks that it's the master, and needs to do the propagation etc. Have I missed something embarassingly obvious here? Any help would really be great!

Thanks

3 posts / 0 new
Last post
For more complete information about compiler optimizations, see our Optimization Notice.

Hi,

Could you provide some more details, please?

1. Exact mpdboot command

2. Output of "which mpiexec"

2. Debug output of

"mpiexec -genv I_MPI_DEBUG 3 -machinefile ~/mpd.hosts -n 4 ./testc"

Thank you in advance,

- Grigory

Hi Grigory,

Thanks for the help - it was the 'which mpiexec' that solved the problem: it was referencing /usr/bin and not the intel mpi bin directory. Pretty silly thing not to have found earlier. Thanks again.

Leave a Comment

Please sign in to add a comment. Not a member? Join today