OpenMP, reduction clause and access violation?

j0e · ‎07-11-2008

Hi all,

Can anyone explain while the following code causes a general access violoation (exception code c0000005) when run in parallel (/Qopenmp is specified):

Program main
implicit noneinteger na
real(8) obj
real(8), allocatable:: a(:) 
na = 100
allocate( a(na) ) 
call sub1 (na, a, obj)
deallocate ( a )
stop
end program main
subroutine sub1(na, a, obj)
implicit noneinteger na
real(8) a(na), obj
integer i, icnt
a = 0.0
obj = 0.0
icnt = 0
!$omp parallel do &!$omp private (obj) &!$omp firstprivate (a) lastprivate (a) &!$omp reduction (+:icnt)do i=1,4
   a(1:na) = real(i)   obj = sum(a(1:na))
   icnt = icnt + 1
   write(6,*) i,': ', obj
end do!$omp end parallel do
write(6,*) 'icnt = ', icnt
return
end subroutine sub1
If I remove the reduction clause, then the code does not cause the access violation, and runs correctly.  
I'm using the latest version of IVF and running on Vista x64.  Also, if i statically allocate arrary a in the
main program, program runs fine.
thanks
-joe