stack overflow when trying to uase openmp directive

[Ralph_Nelson]

Been running with single thread and tried to use a single openmp instruction.

do 95 k = 1, ivfcount
j = ivflist(k)
!$omp parallel DO private(i,j)
do 90 i = 1, nfmaxp2
if (i.le.ncn(j)+2) w(j) = w(j) + (a(i,j) * p(cn(i,j)))
90 continue
!$omp end parallel DO
95 continue

Get the error "forrt1: severe (170): Program Exception - stack overflow" A web search shows this isn't uncommon but trying several fixes that were suggested, haven't fixed the problem.

Running Intel Fortran 11.1 in Visual Studion 2008 on Win7 64-bit.

Thanks for any suggestions.

[TimP]

In effect, you have a reduction operator here. With the syntax you quote, you have a race condition, with multiple threads updating w(j) at the maximum possible rate. It doesn't look like you should be trying OpenMP in the inner reduction loop. Supposing that you wrote
!$omp parallel do private(j,tmp)
do k=1,ivfcount
j = ivflist(k)
tmp = dot_product(a(1:min(nfpmax2,ncn(j)+2),j),p(1:min(nfpmax2,ncn(j)+2),j))
!$omp ordered
w(j)= tmp
!$omp end ordered
enddo

You would not need the ordered if you could assure that ivlist doesn't contain repeated values, if in fact that's what is meant in this code.

[Ralph_Nelson]

Thanks Tim.

Yes, ivflist has no repeated values, just a list of loop values that statisfy a condition.

ivfcount = 0
do 7 j = 1, nelem
if (ivflag(j).ne.1) then
ivfcount = ivfcount +1
ivflist(ivfcount) = j
endif
7 continue

Implementing your suggestion still results in the same failure.

[TimP]

As your search no doubt told you, the most common solutions for stack overflow when introducing OpenMP are attention both to global stack (Microsoft linker properties) and thread stack (KMP_STACKSIZE).

[Ralph_Nelson]

Tim,

Dumb question(s). I assume I can set the global stack using
Configuation Properties -> Linker -> System -> Stack Reserve Size

Is the thread stack variable set as a comand line addition to Fortran?

[Steven_L_Intel1]

You have to define an environment variable, KMP_STACKSIZE, before running the program. It isn't a compile or link option.