[DFTB-Plus-User] dftb+.mpi as spawned process

[Bálint Aradi]

Dear Alex,

thank you for your suggestions.

> As far as I know, all that is necessary for dftb+.mpi to become "spawn
> ready" would be to
> add something like
>  
>    integer :: mpi_comm_parent
> 
>    call mpi_comm_get_parent(mpi_comm_parent,error0)
> 
>    if (mpi_comm_parent.ne.mpi_comm_null) then
>        call mpi_comm_disconnect(mpi_comm_parent,error0)
>    endif              
>    
> right before "call mpi_finalize(error0)". Please, note that testing the
> value of mpi_comm_parent
> as above make the call to mpi_comm_disconnect safe in case dftb+.mpi is
> called from "mpirun".

I've added that to the code in our MPI-branch.
> 
>     if (mympi%master.and.mpi_comm_parent.eq.mpi_comm_null) then
>       stdout = output_unit
>     else
>       stdout = 1
>       open(stdout, file="/dev/null", action="write")
>     end if

This solution, I do no like as a general solution, as for me it is not
trivial at all, that all IO to stdout should be suppressed when DFTB+ is
spawned by other process via mpi_comm_spawn(). One could eventually
think about a flag in the input file (or a command line argument for
DFTB+), which would do that.

  Best regards and a happy new year,

  Bálint

-- 
Dr. Bálint Aradi
Bremen Center for Computational Materials Science, University of Bremen
http://www.bccms.uni-bremen.de/cms/people/b_aradi/


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