1: ! Synchronized printing: Fortran Example

  3: program main
  4: #include <petsc/finclude/petscsys.h>
  5:   use petscmpi  ! or mpi or mpi_f08
  6:   use petscsys

  8:   implicit none
  9:   PetscErrorCode                    :: ierr
 10:   PetscMPIInt                       :: rank, size
 11:   character(len=PETSC_MAX_PATH_LEN) :: outputString

 13:   ! Every PETSc program should begin with the PetscInitialize() routine.

 15:   PetscCallA(PetscInitialize(ierr))

 17:   ! The following MPI calls return the number of processes
 18:   ! being used and the rank of this process in the group

 20:   PetscCallMPIA(MPI_Comm_size(MPI_COMM_WORLD, size, ierr))
 21:   PetscCallMPIA(MPI_Comm_rank(MPI_COMM_WORLD, rank, ierr))

 23:   ! Here we would like to print only one message that represents
 24:   ! all the processes in the group
 25:   write (outputString, *) 'No of Processors = ', size, ', rank = ', rank, '\n'
 26:   PetscCallA(PetscPrintf(PETSC_COMM_WORLD, outputString, ierr))

 28:   write (outputString, *) rank, 'Synchronized Hello World\n'
 29:   PetscCallA(PetscSynchronizedPrintf(PETSC_COMM_WORLD, outputString, ierr))

 31:   write (outputString, *) rank, 'Synchronized Hello World - Part II\n'
 32:   PetscCallA(PetscSynchronizedPrintf(PETSC_COMM_WORLD, outputString, ierr))
 33:   PetscCallA(PetscSynchronizedFlush(PETSC_COMM_WORLD, PETSC_STDOUT, ierr))

 35:   ! Here a barrier is used to separate the two program states.
 36:   PetscCallMPIA(MPI_Barrier(PETSC_COMM_WORLD, ierr))

 38:   write (outputString, *) rank, 'Jumbled Hello World\n'
 39:   PetscCallA(PetscPrintf(PETSC_COMM_SELF, outputString, ierr))

 41:   PetscCallA(PetscFinalize(ierr))
 42: end program main

 44: !/*TEST
 45: !
 46: !   test:
 47: !
 48: !TEST*/