Open MPI logo  Open MPI User's Mailing List Archives   Subject:
[OMPI users] mpi job is blocked From: Richard
(codemonkee_at_[hidden]) Date: 2012-09-25 02:20:58  I have 3
computers with the same Linux system. I have setup the mpi
cluster based on ssh connection. I have tested a very simple mpi
program, it works on the cluster.  To make my story clear, I
name the three computer as A, B and C.  1) If I run the job with
2 processes on A and B, it works. 2) if I run the job with 3
processes on A, B and C, it is blocked. 3) if I run the job with
2 processes on A and C, it works. 4) If I run the job with all
the 3 processes on A, it works.  Using gdb I found the line at
which it is blocked, it is here  #7 0x00002ad8a283043e in
PMPI_Allreduce (sendbuf=0x7fff09c7c578, recvbuf=0x7fff09c7c570,
count=1, datatype=0x627180, op=0x627780, comm=0x627380)     at
pallreduce.c:105 105 err = comm->c_coll.coll_allreduce(sendbuf,
recvbuf, count,  It seems that there is a communication problem
between some computers. But the above