Hi,
When I ran multiple processes in a single machine, the programs are hanging in mpi_allreduce in different points during different runs. I am using 1.3.4. When I used different machines to run the processes, it is OK. Also, when I recompiled open mpi in debug mode, the problem goes away. Since the hangings occurred at different points, I suspect some race/deadlock situations that due to some optimization in openmpi. I used -O3 in compilation with gcc44 and gfortran44. The software I am running in MUMPS (4.10.0). Other platforms (solaris 10) do not have this problem. Any suggestion I should try out? Here is stack: #0 mca_btl_sm_component_progress () at btl_sm_component.c:387 #1 0x00002b304a4e1f3a in opal_progress () at runtime/opal_progress.c:207 #2 0x00002b3049e20fa5 in opal_condition_wait (count=2, requests=0x7fff1376d850, statuses=0x0) at ../opal/threads/condition.h:99 #3 ompi_request_default_wait_all (count=2, requests=0x7fff1376d850, statuses=0x0) at request/req_wait.c:262 #4 0x00002b304ecb4952 in ompi_coll_tuned_allreduce_intra_recursivedoubling ( sbuf=<value optimized out>, rbuf=0x14c9da10, count=1, dtype=0x2b304a085d40, op=0x2b304a07d280, comm=0x14ca34d0, module=0x14ca0500) at coll_tuned_allreduce.c:223 #5 0x00002b3049e36384 in PMPI_Allreduce (sendbuf=0x14c9d8d0, recvbuf=0x14c9da10, count=1, datatype=<value optimized out>, op=0x2b304a07d280, comm=0x14ca34d0) at pallreduce.c:102 #6 0x00002b304a0b9bd3 in mpi_allreduce_f (sendbuf=0x14c9d8d0 "", recvbuf=0x14c9da10 "", count=0x626eb0, datatype=<value optimized out>, op=0x626ec0, comm=<value optimized out>, ierr=0x7fff1376e530) at pallreduce_f.c:77 #7 0x000000000049dbd4 in dmumps_142 (id=...) at dmumps_part5.F:5570 Thanks. Willia