Race Conditions/1

In the following code the result varies unpredictably based on detailed order of execution of each section
wrong answers produced without warning
fixing the example, we choose the assignments to occur in order A, B, C
- icount forces this order
- FLUSH forces the update of the shared variable

C$omp parallel sections

A = B + C

c$omp section

B = A + C

c$omp section

C = B + A

c$omp end parallel sections

icount = 0

C$omp parallel sections

A = B + C

icount = 1

c$omp flush (icount)

c$omp section

1000 continue

if(icount.lt.1) goto 1000

B = A + C

icount = 2

c$omp flush (icount)

c$omp section

2000 continue

if(icount.lt.2) goto 2000

C = B + A

c$omp end parallel sections