I just figured it out my self: MPI_Ibarrier returns MPI_REQUEST_NULL. Sorry for the noise! Best, Nils On 07.06.2018 11:51, Nils-Arne Dreier wrote:

Dear MPICH community,

the following program deadlocks when executed with MPICH 3.2 (Debian stretch) on a single rank.

barrier_waitany.cc #include <mpi.h>

int main(int argc, char** argv){   MPI_Request req[2];   int buf;   int index;   MPI_Init(&argc, &argv);   MPI_Ibarrier(MPI_COMM_WORLD, &req[0]);   MPI_Irecv(&buf, 1, MPI_INT, 0, 0, MPI_COMM_WORLD, &req[1]);   MPI_Waitany(2, req, &index, MPI_STATUS_IGNORE);   MPI_Finalize();   return 0; }

Compile with: mpic++ -g -std=c++14 -Wall mpi_barrier_waitany.cc -o mpi_barrier_waitany

Execute with: mpirun -n 1 ./barrier_waitany

Best, Nils

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