I was able to make some progress by using this <https://github.com/bert9bert/ParallelForest/blob/master/src/Makevars> as a reference. Now:
*This is my makevars:* ##### Compiler flags ##### PKG_FCFLAGS = $(SHLIB_OPENMP_FFLAGS) PKG_LIBS = $(SHLIB_OPENMP_CFLAGS) ##### Phony target for R's build system to invoke ##### all: $(SHLIB) ##### Clean target ##### clean: rm -f *.o *.mod And when I run my hello world function all the threads are used regardless of what i specify: > hello(ncores = 2) Hello from 1 Hello from 3 Hello from 0 Hello from 9 Hello from 8 Hello from 2 Hello from 6 Hello from 10 Hello from 11 Hello from 5 Hello from 7 Hello from 4 $ncores [1] 2 What am I missing? My Fortran subroutine uses !$call omp_set_num_threads(ncores) to set the number of threads. Why is this not working? How can I fix it? Thanks a lot for the help Ignacio On Fri, Feb 1, 2019 at 4:51 PM Ignacio Martinez <ignaci...@gmail.com> wrote: > 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 > > [[alternative HTML version deleted]] ______________________________________________ R-devel@r-project.org mailing list https://stat.ethz.ch/mailman/listinfo/r-devel
