Initialize MPI with requested threading support, maximizing support for client codes

Author: AlexBuccheri

src/fortuno_mpi/mpienv.f90

@@ -5,8 +5,8 @@
 !> Contains a type to deal with the mpi environment
 module fortuno_mpi_mpienv
   use mpi_f08, only : MPI_Allreduce, MPI_CHAR, MPI_Comm, MPI_Comm_rank, MPI_Comm_size,&
-      & MPI_COMM_WORLD, MPI_IN_PLACE, MPI_Init, MPI_INTEGER, MPI_Finalize, MPI_PROD, MPI_Recv,&
-      & MPI_Send, MPI_Status
+      & MPI_COMM_WORLD, MPI_IN_PLACE, MPI_Init_thread, MPI_INTEGER, MPI_Finalize, MPI_PROD, MPI_Recv,&
+      & MPI_Send, MPI_Status, MPI_THREAD_MULTIPLE
   implicit none
 
   private
@@ -34,15 +34,18 @@ module fortuno_mpi_mpienv
 contains
 
   !> Initializes the MPI environment
+  !!
+  !! Full threading support with MPI is requested to maximize support
+  !! for client codes.
   subroutine init_mpi_env(this)
 
     !> Instance
     type(mpi_env), intent(out) :: this
 
-    integer :: ierror
+    integer :: ierror, provided
 
-    call MPI_Init(ierror)
-    if (ierror /= 0) error stop "MPI_Init failed in init_mpi_env"
+    call MPI_Init_thread(MPI_THREAD_MULTIPLE, provided)
+    if (ierror /= 0) error stop "MPI_Init_thread failed in init_mpi_env"
     this%comm = MPI_COMM_WORLD
     call MPI_Comm_size(this%comm, this%nranks, ierror)
     if (ierror /= 0) error stop "MPI_Comm_size failed in init_mpi_env"