I am trying to understand how communicator attributes work, so I found http://stackoverflow.com/questions/25198353/callbacks-provided-in-mpi-comm-c..., which contains a nice example (the code in http://stackoverflow.com/a/25205611/2189128). However, the posted output of this code is: $ mpirun -np 1 ./comm-attr In ibcast_copy: keyval = 10 In ibcast_delete: keyval = 10 In ibcast_delete: keyval = 10 Whereas I observe: $ mpirun -np 1 ./a.out In ibcast_copy: keyval = -1539309568 In ibcast_delete: keyval = -1539309568 Can anyone help me understand what the correct output of this program is? If it is not what I am seeing, is this a bug in MPICH or am I doing something wrong? I am using MPICH git from November 2015, so I will git pull && ./autogen.sh && $CONFIGUREMAKEINSTALL and try again just to be sure. Thanks, Jeff $ mpirun --version HYDRA build details: Version: 3.2 Release Date: unreleased development copy CC: icc CXX: icpc F77: ifort F90: ifort Configure options: '--disable-option-checking' '--prefix=/opt/mpich/dev/intel/default' 'CC=icc' 'CXX=icpc' 'FC=ifort' 'F77=ifort' '--enable-cxx' '--enable-fortran' '--enable-threads=runtime' '--enable-g=dbg' '--with-pm=hydra' '--enable-wrapper-rpath' '--enable-static' '--enable-shared' '--cache-file=/dev/null' '--srcdir=../../../../src/pm/hydra' 'CFLAGS= -g -O2' 'LDFLAGS=' 'LIBS=-lpthread ' 'CPPFLAGS= -I/Users/jrhammon/Work/MPI/MPICH/git/build/src/mpl/include -I/Users/jrhammon/Work/MPI/MPICH/git/src/mpl/include -I/Users/jrhammon/Work/MPI/MPICH/git/src/openpa/src -I/Users/jrhammon/Work/MPI/MPICH/git/build/src/openpa/src -D_REENTRANT -I/Users/jrhammon/Work/MPI/MPICH/git/build/src/mpi/romio/include' Process Manager: pmi Launchers available: ssh rsh fork slurm ll lsf sge manual persist Topology libraries available: hwloc Resource management kernels available: user slurm ll lsf sge pbs cobalt Checkpointing libraries available: Demux engines available: poll select -- Jeff Hammond [email protected] http://jeffhammond.github.io/ _______________________________________________ discuss mailing list [email protected] To manage subscription options or unsubscribe: https://lists.mpich.org/mailman/listinfo/discuss