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);
xbt_free(instance->comm_world);
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);
xbt_free(instance->comm_world);