Try using MPI_Comm_remotr_size. As this is an intercommunicator that will give
the number of ranks for send/recv.
> On Apr 13, 2018, at 7:34 AM, Florian Lindner <mailingli...@xgm.de> wrote:
>
> Hello,
>
> I have this piece of code
>
> PtrRequest MPICommunication::aSend(double *itemsToSend, int size, int
> rankReceiver)
> {
> rankReceiver = rankReceiver - _rankOffset;
> int comsize = -1;
> MPI_Comm_size(communicator(rankReceiver), &comsize);
> TRACE(size, rank(rankReceiver), comsize);
>
>
> MPI_Request request;
> MPI_Isend(itemsToSend,
> size,
> MPI_DOUBLE,
> rank(rankReceiver),
> 0,
> communicator(rankReceiver),
> &request);
>
> return PtrRequest(new MPIRequest(request));
> }
>
> While there are quite some calls you don't know, it's basically a wrapper
> around Isend.
>
> The communicator returned by communicator(rankReceiver) is an
> inter-communicator!
>
> The TRACE call prints:
>
> [1,1]<stdout>:(1) 14:30:04 [com::MPICommunication]:104 in aSend: Entering
> aSend
> [1,1]<stdout>: Argument 0: size == 50
> [1,1]<stdout>: Argument 1: rank(rankReceiver) == 1
> [1,1]<stdout>: Argument 2: comsize == 2
> [1,0]<stdout>:(0) 14:30:04 [com::MPICommunication]:104 in aSend: Entering
> aSend
> [1,0]<stdout>: Argument 0: size == 48
> [1,0]<stdout>: Argument 1: rank(rankReceiver) == 0
> [1,0]<stdout>: Argument 2: comsize == 2
>
> So, on rank 1 we send to rank = 1 on a communicator with size = 2.
>
> Still, rank 1 crashes with:
>
> [neon:80361] *** An error occurred in MPI_Isend
> [neon:80361] *** reported by process [1052966913,1]
> [neon:80361] *** on communicator
> [neon:80361] *** MPI_ERR_RANK: invalid rank
> [neon:80361] *** MPI_ERRORS_ARE_FATAL (processes in this communicator will
> now abort,
> [neon:80361] *** and potentially your MPI job)
>
> your collegues from mpich print
>
> [1] Fatal error in PMPI_Isend: Invalid rank, error stack:
> [1] PMPI_Isend(149): MPI_Isend(buf=0x560ddeb02100, count=49, MPI_DOUBLE,
> dest=1, tag=0, comm=0x84000005,
> request=0x7ffd528989c0) failed
> [1] PMPI_Isend(97).: Invalid rank has value 1 but must be nonnegative and
> less than 1
>
> [0] Fatal error in PMPI_Isend: Invalid rank, error stack:
> [0] PMPI_Isend(149): MPI_Isend(buf=0x564b74c9edd8, count=1, MPI_DOUBLE,
> dest=1, tag=0, comm=0x84000006,
> request=0x7ffe5848d9f0) failed
> [0] PMPI_Isend(97).: Invalid rank has value 1 but must be nonnegative and
> less than 1
>
> but MPI_Comm_size also returns 2.
>
> Do you have any idea where to look to find out what is going wrong here? Esp.
> with the communicator being an inter-com.
>
> Best Thanks,
> Florian
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