Hi everybody,
I'm trying to develop an R package with Fortran and OpenMP. I wrote a
simple hello world but I'm not able to set the number of threads. I found this
old email chain
<http://r.789695.n4.nabble.com/Set-the-number-of-threads-using-openmp-with-C-td2284685.html>
and
I tried to set my compile instructions accordingly but i had no luck.
*This is my makevars:*
PKG_FCFLAGS="-fno-stack-protector"
F90FLAGS = "-fopenmp"
LDFLAGS = "-fopenmp"
*This is my Fortran module:*
module hello_openmp
use omp_lib
implicit none
contains
subroutine hello(ncores) bind(C, name="hello_")
use, intrinsic :: iso_c_binding,
only : c_double, c_int
integer(c_int), intent(in) :: ncores
integer :: iam
! Specify number of threads to use:
!$call omp_set_num_threads(ncores)
!$omp parallel private(iam)
iam=omp_get_thread_num()
!$omp critical
write(*,*) 'Hello from', iam
!$omp end critical
!$omp end parallel
end subroutine hello
end module hello_openmp
*and this is my R function:*
#'@export
#'@useDynLib helloOpenMP, .registration = TRUE
hello <- function(ncores=4) {
.Fortran("hello", ncores = as.integer(ncores))
}
*Alas, when I call hello things only run with one thread:*
> hello(ncores = 2)$ncores
Hello from 0
[1] 2
Could you point me in the right direction? What am I missing?
Thanks,
Ignacio
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