[johndeas]

Hi,

I need my master processor to carry out some operations on some files. I would like all the other processors to pause while this is going on, as their behaviour might be affected by the non completion of the task on the master proc.

I have read about MPI_barrier() which seems to be what I need:

if not on the masterProc:
    MPI_barrier()
else:
    carry out operation
    MPI_barrier()

Is it possible to do this directly using OpenFOAM commands and if not, is it possible to use the vanilla MPI_barrier() ?

In that case what arguments should be put in:

int MPI_Barrier ( MPI_Comm comm )

?

Thanks !

[fra76]

When I need this, I usually do a reduction, as MPI_barrier is not exposed by Pstream, as far as I know.

I.e.:

if (Pstream.master())
{
   carry out operation
}
{
    label tmp = Pstream.myProcNo();
    reduce(tmp,sumOp<label>());
}

At the reduce statement, all the processors must pass together, so the effect is like MPI_barrier even if with a very low unnecessary traffic.

Hope this helps,
Francesco

[johndeas]

Since I am putting a lot of commands, a proper MPI_barrier might have helped, but, thank you for you advice, will use it !