! Synchronized printing: Fortran Example

program main
#include <petsc/finclude/petscsys.h>
  use petscmpi  ! or mpi or mpi_f08
  use petscsys

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

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

  PetscCallA(PetscInitialize(ierr))

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

  PetscCallMPIA(MPI_Comm_size(MPI_COMM_WORLD, size, ierr))
  PetscCallMPIA(MPI_Comm_rank(MPI_COMM_WORLD, rank, ierr))

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

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

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

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

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

  PetscCallA(PetscFinalize(ierr))
end program main

!/*TEST
!
!   test:
!
!TEST*/