Segfault with OpenMP and combination of Fortran/C

[sonicato]

I have an error by executing a combination Fortran/C program with OpenMP pragma.

C source code:

#include 
#include 

extern void fentry_( int * );

int main(){
 int level=4, num;

 num = omp_get_max_threads();
 printf("omp threads = %d
",num);
 fflush(stderr);
 fflush(stdout);
 
 fentry_( &level );
 return 0;
}

Fortran source code:

module fe
 use omp_lib
 implicit none
 
 type matrixStruct
 real(kind=8), dimension(:,:), allocatable :: matrix
 end type matrixStruct

 contains

 subroutine f1(level)
 integer(kind=4) :: level, i, j, m
 type(matrixStruct), dimension(:), allocatable :: struct

 allocate( struct(1:level) )

 do i=1, level
 m = ((2**i)+1)**2
 allocate( struct(i)%matrix(1:m,1:m) )

 write(*,*) "matrix ", i, " befor, size=", size(struct(i)%matrix(:,1)), size(struct(i)%matrix(1,:))
 do j=1, m
 write(*,*) struct(i)%matrix(:,j)
 end do

 !$omp parallel do shared(m, struct) private(i, j)
 do j=1, m
 struct(i)%matrix(:,j) = 0
 end do
 end do

 do i=1, level
 m = ((2**i)+1)**2
 write(*,*) "matrix ", i, " after, size=", size(struct(i)%matrix(:,1)), size(struct(i)%matrix(1,:))
 do j=1, m
 write(*,*) struct(i)%matrix(:,j)
 end do
 end do

 do i=1, level
 deallocate( struct(i)%matrix )
 end do
 deallocate( struct )
 end subroutine f1
end module fe

subroutine fentry(level)
 use fe
 integer(kind=4) :: level

 call f1(level)
end subroutine fentry

The source code was compiled with the flags "-g -O2 -mcpu=itanium2-p9000 -mtune=itanium2-p9000 -openmp" and the compiler "INTEL C/C++ Compiler Version 10.1 Build 015" and "INTEL Fortran Compiler Version 10.1 Build 015".

Running the program end in a segfault.

I ruled out all usual suspects.

Any help would be appreciated.
Thanks in advance,
Jens

[TimP]

I can't get a properly formatted copy of your source code to try it.

As I would take your comment about having tried all evident solutions to include such measures as setting thread stack size by kmp_stacksize (environment variable or function call), it seems you have excluded anyone from commenting.

[sonicato]

I have added an attachment with the source code, copy the 2 parts in the .txt file to a .c file and a .f90 file.

Yes, I have tried to set KMP_STACKSIZE and also to compile with "-heap-arrays 0", but no changes.

The program ends after printing the first matrix in the first loop.

[jimdempseyatthecove]

Jens,

OpenMP in FORTRAN require an !$OMP END xxx at the end of parallel regions. In this case you are missing

!$omp end parallel do

after the statement that ends the do loop that was parallized

 !$omp parallel do shared(m, struct) private(i, j)
 do j=1, m
 struct(i)%matrix(:,j) = 0
 end do
 !$omp end parallel do

Jim Dempsey

[sonicato]

I am not sure, if this "!$omp end ..." statement is realy necessary,
but the error also occurs with this statement.

[sonicato]

I think, I have the solution.
The privat(i) is wrong, firstprivate(i) seems to be correct, else i has not the value like befor the omp pragma.

[jimdempseyatthecove]

Sonicato,

In looking at your parallelloop you want shared(i)

The parallel loop is inside the do loop iterating on i. i must be passed into the parallel region (and not modified in there).

Jim Dempsey