- xbt_dict_foreach((xbt_dict_t) smpi_instances, cursor, name, instance) {
- while (smpi_group_unuse(smpi_comm_group(instance->comm_world)) > 0);
+ xbt_dict_foreach(smpi_instances, cursor, name, instance) {
+ if(instance->comm_world!=MPI_COMM_NULL)
+ while (smpi_group_unuse(smpi_comm_group(instance->comm_world)) > 0);