PGI, OpenMP and namelist in Fortran - fortran

Question

I encounter a problem while trying to read a namelist in a Fortran program, using OpenMP and the Portland Group compiler.
What I am trying to do is simple: I call a read_namelist subroutine in a SINGLE region, where I initialize the parameters I want to read from the namelist, and then I open, read, close the namelist. The parameters I'm reading in the namelist are threadprivate, and I spread them to the other threads after the reading.
While it works perfectly well with GNU and Intel compilers, it fails with PGI and I cannot get why. I get no error, but the read parameters are equal to the default parameters, not the ones I read from the namelist.
Here is an example of what I am trying to do:
program read_input
!$ use OMP_LIB
use params
implicit none
integer :: rank=0, nthreads=1
!$OMP PARALLEL DEFAULT(PRIVATE)
!$ rank = OMP_GET_THREAD_NUM()
!$ nthreads = OMP_GET_NUM_THREADS()
!$OMP SINGLE
print*, 'There is ', nthreads, ' threads running'
call read_nml
!$OMP END SINGLE COPYPRIVATE(nx, ny, nz)
print*, 'Rank: ', rank
print*, 'nx, ny, nz: ', nx, ny, nz
!$OMP END PARALLEL
contains
subroutine read_nml
use params
implicit none
namelist /input_params/ nx, ny, nz
call default_parameters
print*, 'nx, ny, nz (default): ', nx, ny, nz
open(unit=1, file='input', status='old')
read(1, input_params)
close(1)
print*, 'nx, ny, nz (read): ', nx, ny, nz
return
end subroutine read_nml
subroutine default_parameters
use params
implicit none
nx = 2; ny = 2; nz = 2
return
end subroutine default_parameters
end program read_input
the module params is very simple and contains only:
module params
integer :: nx, ny, nz
!$OMP THREADPRIVATE(nx, ny, nz)
end module params
Compiling with pgfortran, here is the output I get (with 2 threads):
Start program: read_input
There is 2 threads running
nx, ny, nz (default): 2 2 2
Rank: 0
nx, ny, nz: 2 2 2
Rank: 1
nx, ny, nz: 2 2 2
And if I compile the same piece of code with Intel or GNU compilers (still with 2 threads):
Start program: read_input
There is 2 threads running
nx, ny, nz (default): 2 2 2
nx, ny, nz (read): 10 10 10
Rank: 0
nx, ny, nz: 10 10 10
Rank: 1
nx, ny, nz: 10 10 10
Any thought or hint will be appreciated!

Answer 1

I don't get the exact reason, but at least I found a workaround, playing with the code.
If the parameters read in the namelist are private in the subroutine, they can be read with no problem; therefore replacing
call read_nml
by
call read_nml(nx, ny, nz)
and the subroutine read_nml by
subroutine read_nml(nx, ny, nz)
implicit none
integer :: nx, ny, nz
namelist /input_params/ nx, ny, nz
call default_parameters
print*, 'nx, ny, nz (default): ', nx, ny, nz
open(unit=1, file='input', status='old')
read(1, input_params)
close(1)
print*, 'nx, ny, nz (read): ', nx, ny, nz
return
end subroutine read_nml
works well. I guess it is once again a problem of status (private) of the attributes, but I don't get why Intel and GNU compilers handled it with no problem whereas PGI compiler is not able to handle it. Actually, that is why the parameters were threadprivate in my module, to prevent this kind of behaviour. If somebody can give me a better answer than the one I have, I'm still interested!