MPI_IN_PLACE problem in openmpi-1.8.3 (FORTRAN) #259
Description
There seems to be a bug at using MPI_IN_PLACE at this release, using it will return zero value.
program main
use mpi
implicit none
integer :: ierr, rank
real(8) :: a
call MPI_INIT(ierr)
call MPI_COMM_RANK(MPI_COMM_WORLD, rank, ierr)
select case (rank)
case (0)
a=10._8
case (1)
a=-300._8
case(2)
a=-150._8
end select
print*,rank,a
call MPI_Allreduce(MPI_IN_PLACE,a,1,MPI_DOUBLE_PRECISION,MPI_MIN,MPI_COMM_WORLD,ierr)
print*,rank,"---",a
call MPI_Finalize(ierr)
end program and compiling the program with mpif90 and running it will result
mpirun -np 3 ./a.out
0 10.000000000000000
1 -300.00000000000000
2 -150.00000000000000
0 --- 0.0000000000000000
1 --- 0.0000000000000000
2 --- 0.0000000000000000Not using MPI_IN_PLACE will give the correct result.