topic Coarray runtime bug in Intel® Fortran Compiler

Coarray runtime bug

NCarlson — Mon, 04 Apr 2022 18:09:57 GMT

I'm hitting a segfault with some coarray code when running with 1 image. I've reduced it to this test case:

integer :: x(10), y(10) call foo(x, y) contains subroutine foo(src, dest) integer, intent(in), target :: src(:) integer, intent(inout) :: dest(:) type box integer, pointer :: data(:) end type type(box), allocatable :: buffer[:] allocate(buffer[*]) if (this_image() == 1) buffer%data => src sync all dest = buffer[1]%data end subroutine end

I'm using ifort 2021.5.0 and using these compiler options: -coarray -coarray-num-images=1

I'm also setting

export I_MPI_DEVICE=shm export I_MPI_FABRICS=shm

per this Intel page in order to keep coarray executables from pounding on the loopback network device and getting really crappy performance (I'm running on a single shared-memory node).

With this setup the executable segfaults, however if I don't set those I_MPI variables then the test case executes without error.

Re: Coarray runtime bug

Barbara_P_Intel — Tue, 05 Apr 2022 20:36:00 GMT

I duplicated your issue. I'll keeping looking at that.

There are two workarounds that I see.

Compile with -coarray=shared.
Create a config file. The article has some details. It's written for distributed environments, but the concepts are the same for shared.

Re:Coarray runtime bug

Barbara_P_Intel — Fri, 08 Apr 2022 18:10:28 GMT

I learned that there is a known issue with MPI that applies to your case and a workaround.

Single-process run with I_MPI_FABRICS=shm may lead to crash. Please use out-of-box settings or I_MPI_FABRICS=shm:ofi instead.

It worked for me with your reproducer.

This will be documented in the MPI Library Release Notes in the next release.