In artdaq v3 systems, art is started at begin run time, instead of at program start. This means that mpirun cannot be used to start all of the processes in an artdaq system, which in turn means that transfers from art processes to downstream artdaq processes cannot use MPI. There is support in the MPI standard for connecting to processes after program start, which should allow MPI transfer to work under these conditions.
This issue has been migrated from https://cdcvs.fnal.gov/redmine/issues/23386 (FNAL account required) Originally created by @eflumerf on 2019-10-07 16:43:58
In artdaq v3 systems, art is started at begin run time, instead of at program start. This means that mpirun cannot be used to start all of the processes in an artdaq system, which in turn means that transfers from art processes to downstream artdaq processes cannot use MPI. There is support in the MPI standard for connecting to processes after program start, which should allow MPI transfer to work under these conditions.