How does the SECTIONS directive in OpenMP distribute work?

Question

In OpenMP when using omp sections, will the threads be distributed to the blocks inside the sections, or will each thread be assigned to each sections?

Answer 1

The idea of parallel sections is to give the compiler a hint that the various (inner) sections can be performed in parallel, for example:

#pragma omp parallel sections
{
   #pragma omp section
   {
      /* Executes in thread 1 */
   } 
   #pragma omp section
   {
      /* Executes in thread 2 */
   } 
   #pragma omp section
   {
      /* Executes in thread 3 */
   } 
   /* ... */
}

This is a hint to the compiler and not guaranteed to happen, though it should. Your output is kind of what is expected; it says that there are #sections being executed in thread id 1, and in thread 2. The output order is non-deterministic as you don't know what thread will run first.