Hi folks, I have a really strange problem: a super simple MPI test program (see below) runs successfully for all users when executed on 4 processes in 1 node, but hangs for user A and runs successfully for user B when executed on 8 processes in 2 nodes. The executable used is the same and the appfile used is also the same for user A and user B. Both users launch it by
mpirun --app appfile where the content of 'appfile' is -np 1 -host node1 -wdir /tmp/test ./test -np 1 -host node1 -wdir /tmp/test ./test -np 1 -host node1 -wdir /tmp/test ./test -np 1 -host node1 -wdir /tmp/test ./test for the single node run with 4 processes and is replaced by -np 1 -host node1 -wdir /tmp/test ./test -np 1 -host node1 -wdir /tmp/test ./test -np 1 -host node1 -wdir /tmp/test ./test -np 1 -host node1 -wdir /tmp/test ./test -np 1 -host node2 -wdir /tmp/test ./test -np 1 -host node2 -wdir /tmp/test ./test -np 1 -host node2 -wdir /tmp/test ./test -np 1 -host node2 -wdir /tmp/test ./test for the 2-node run with 8 processes. Just to recap, the single node run works for both user A and user B, but the 2-node run only works for user B and it hangs for user A. It does respond to Ctrl-C though. Both users use bash, have set up passwordless ssh, are able to ssh from node1 to node2 and back, have the same PATH and use the same 'mpirun' executable. At this point I've run out of ideas what to check and debug because the setups look really identical. The test program is simply #include <stdio.h> #include <mpi.h> int main( int argc, char **argv ) { int node; MPI_Init( &argc, &argv ); MPI_Comm_rank( MPI_COMM_WORLD, &node ); printf( "First Hello World from Node %d\n", node ); MPI_Barrier( MPI_COMM_WORLD ); printf( "Second Hello World from Node %d\n",node ); MPI_Finalize( ); return 0; } I also asked both users to compile the test program separately, and the resulting executable 'test' is the same for both indicating again that identical gcc, mpicc, etc, is used. Gcc is 4.5.1 and openmpi is 1.5. and the interconnect is infiniband. I've really run out of ideas what else to compare between user A and B. Thanks for any hints, Daniel -- Psss, psss, put it down! - http://www.cafepress.com/putitdown -- Psss, psss, put it down! - http://www.cafepress.com/putitdown