我有一个简单的MPI_SENDRECV程序，用于在2D数组之间交换数据。 This帖子有同样的问题，这是由于在MPI_SENDRECV电话中输入的MPI类型，与实际发送/接收的内容不匹配。在下面的代码中，我尝试了交换双精度，单精度或整数，它们都产生了相同的行为。
program main
use, intrinsic :: iso_fortran_env, sp=>real32, dp=>real64
use mpi
implicit none
integer :: ii, jj
integer :: nprocs, myid
integer :: ierror, stat
integer :: Xsrc, Xdes, Ysrc, Ydes
integer, parameter :: grid_nx = 4
integer, parameter :: grid_ny = 4
integer, parameter :: proc_nx = 4 / 2
integer, parameter :: proc_ny = 4 / 2
integer, parameter :: buf = 1
real(dp), allocatable, dimension(:,:) :: array
! MPI init
call MPI_INIT(ierror)
call MPI_COMM_SIZE(MPI_COMM_WORLD, nprocs, ierror)
call MPI_COMM_RANK(MPI_COMM_WORLD, myid, ierror)
print'(A,I1,A,I1,A)', "myid = ", myid, " out of ", nprocs, " processors."
select case(myid)
case(0)
Xsrc = MPI_PROC_NULL; Xdes = 1
Ysrc = MPI_PROC_NULL; Ydes = 2
case(1)
Xsrc = 0; Xdes = MPI_PROC_NULL
Ysrc = MPI_PROC_NULL; Ydes = 3
case(2)
Xsrc = MPI_PROC_NULL; Xdes = 3
Ysrc = 0; Ydes = MPI_PROC_NULL
case(3)
Xsrc = 2; Xdes = MPI_PROC_NULL
Ysrc = 1; Ydes = MPI_PROC_NULL
end select
! Init array
allocate(array(0-buf:proc_nx-1+buf,0-buf:proc_ny-1+buf))
array(:,:) = -100._dp
do jj=0,proc_ny-1
do ii=0,proc_nx-1
array(ii,jj) = (myid+1)*100._dp*(ii + 10._dp * jj) + myid * 10._dp
end do
end do
if(myid==0) print*, "***************************************"
! X buffer points
call mpi_sendrecv(array( 0, 0:proc_ny-1), proc_nx, MPI_DOUBLE, Xsrc, 200,&
& array(-buf, 0:proc_ny-1), proc_nx, MPI_DOUBLE, Xsrc, 100,&
& MPI_COMM_WORLD, stat, ierror)
call mpi_sendrecv(array(proc_nx-1, 0:proc_ny-1), proc_nx, MPI_DOUBLE, Xdes, 100,&
& array(proc_nx , 0:proc_ny-1), proc_nx, MPI_DOUBLE, Xdes, 200,&
& MPI_COMM_WORLD, stat, ierror)
! Y buffer points
call mpi_sendrecv(array(0:proc_nx-1, 0), proc_ny, MPI_DOUBLE, Ysrc, 300, &
& array(0:proc_nx-1,-buf), proc_ny, MPI_DOUBLE, Ysrc, 400, &
& MPI_COMM_WORLD, stat, ierror)
call mpi_sendrecv(array(0:proc_nx-1, proc_ny-1), proc_ny, MPI_DOUBLE, Ydes, 400, &
& array(0:proc_nx-1, proc_ny ), proc_ny, MPI_DOUBLE, Ydes, 300, &
& MPI_COMM_WORLD, stat, ierror)
print'(A,I1,A,I1,A)', "myid = ", myid, " out of ", nprocs, " processors."
call MPI_FINALIZE(ierror)
end program main
我用以下代码运行上面的代码：
mpirun -np 4 ./a.out
输出（并不总是这个顺序）：
myid = 1 out of 4 processors.
myid = 2 out of 4 processors.
myid = 3 out of 4 processors.
myid = 0 out of 4 processors.
***************************************
myid = 0 out of 4 processors.
myid = 0 out of 4 processors.
myid = 0 out of 4 processors.
myid = 0 out of 4 processors.
如您所见，我的处理器等级在通话后会发生变化。我可能正在访问我不认为的内存部分。我是MPI的新手，所以我希望我没有犯任何愚蠢的错误。