Set number of threads using omp_set_num_threads() to 2, but omp_get_num_threads() returns 1

Question

I have the following C/C++ code using OpenMP:

    int nProcessors=omp_get_max_threads();
    if(argv[4]!=NULL){
        printf(\"argv[4]: %s\\n\",argv[4]);
              


        

Answer 1

The omp_get_num_threads() call returns 1 in the serial section of the code. See Link

So you need to have parallel code to get the correct value, here how your code should look like:

#include 
#include 

int main (int argc, const char * argv[])
{
    int nProcessors = omp_get_max_threads();

    std::cout<

This code produces:

2

1
0    tid
2    nThreads
0    tid
2    nThreads
0    tid
2    nThreads
1    tid
2    nThreads
1    tid
2    nThreads

It seems that you have either open mp not enabled or your loop is not in the form that can be parallized by openmp