HI Folks, MPICH/hydra is happy with libCFG_noMCW, even with all the sleeps removed. I ran up to 36 ranks with hydra/mpich and didn’t see a problem. Its not so happy with the other tests, I think they are buggy. Here’s what I get for libCFG_noMCW_multiport hpp@sn-fey1:/usr/projects/hpctools/hpp/mpi_sessions_code_sandbox>mpiexec -n 8 ./libCFG_noMCW_multiport process 1 (MPI_COMM_WORLD) now calling barrier on MPI_COMM_WORLD process 3 (MPI_COMM_WORLD) now calling barrier on MPI_COMM_WORLD process 4 (MPI_COMM_WORLD) calling from group thingy rank 4 non-trivial use-case: target group size 4, localGroup size 1 rank 4 opening port process 5 (MPI_COMM_WORLD) now calling barrier on MPI_COMM_WORLD process 6 (MPI_COMM_WORLD) calling from group thingy rank 6 non-trivial use-case: target group size 4, localGroup size 1 rank 6 opening port process 7 (MPI_COMM_WORLD) now calling barrier on MPI_COMM_WORLD process 0 (MPI_COMM_WORLD) calling from group thingy rank 0 non-trivial use-case: target group size 4, localGroup size 1 process 2 (MPI_COMM_WORLD) calling from group thingy rank 2 non-trivial use-case: target group size 4, localGroup size 1 rank 2 opening port rank 2 opened port tag#0$description#sn-fey1.lanl.gov$port#55566$ifname#128.165.227.181$ rank 2 publishing port tag#0$description#sn-fey1.lanl.gov$port#55566$ifname#128.165.227.181$ using name foobar10 round 1 rank 4 opened port tag#0$description#sn-fey1.lanl.gov$port#45508$ifname#128.165.227.181$ rank 4 publishing port tag#0$description#sn-fey1.lanl.gov$port#45508$ifname#128.165.227.181$ using name foobar10 round 2 rank 6 opened port tag#0$description#sn-fey1.lanl.gov$port#52388$ifname#128.165.227.181$ rank 6 publishing port tag#0$description#sn-fey1.lanl.gov$port#52388$ifname#128.165.227.181$ using name foobar10 round 3 rank 2 published port tag#0$description#sn-fey1.lanl.gov$port#55566$ifname#128.165.227.181$ using name foobar10 round 1 rank 2 accepting on port tag#0$description#sn-fey1.lanl.gov$port#55566$ifname#128.165.227.181$ (localSize 1) Fatal error in PMPI_Publish_name: Invalid service name (see MPI_Publish_name), error stack: PMPI_Publish_name(134): MPI_Publish_name(service="foobar10 round 2", MPI_INFO_NULL, port="tag#0$description#sn-fey1.lanl.gov$port#45508$ifname#128.165.227.181$") failed MPID_NS_Publish(67)...: Lookup failed for service name foobar10 round 2 Fatal error in PMPI_Publish_name: Invalid service name (see MPI_Publish_name), error stack: PMPI_Publish_name(134): MPI_Publish_name(service="foobar10 round 3", MPI_INFO_NULL, port="tag#0$description#sn-fey1.lanl.gov$port#52388$ifname#128.165.227.181$") failed MPID_NS_Publish(67)...: Lookup failed for service name foobar10 round 3 If I have a chance I”ll play with this test and see if I can get it to work. hmm.. maybe hydra doesn’t like the whitespace publish names. Howard -- Howard Pritchard B Schedule HPC-ENV Office 9, 2nd floor Research Park TA-03, Building 4200, Room 203 Los Alamos National Laboratory