MPI serial port main function

int main (int argc, char *argv[])
 {
 //some serial code goes here
 parallel_function(arg1, arg2);
 //some more serial code goes here
}

void parallel_function (int arg1, int arg2)
{
 //init MPI and do some stuff in parallel
 MPI_Init(NULL, NULL);
 MPI_Comm_size(MPI_COMM_WORLD, &p);
 MPI_Comm_rank(MPI_COMM_WORLD, &my_rank);
 //now do some parallel stuff
 //....
 //finalize to end MPI??
 MPI_Finalize(); 
}

This is a very basic MPI question, but I can’t surround it. I have one The main function is to call another function that uses MPI. The main function I want is serial execution, and the other function is executed in parallel. My code is like this:

int main (int argc, char *argv[])
{
 //some serial code goes here
 parallel_function(arg1, arg2);
 //some more serial code goes here
}

void parallel_function(int arg1, int arg2)
{
 //init MPI and do some stuff in parallel
 MPI_Init(NULL, NULL);
 MPI_Comm_size(MPI_COMM_WORLD, &p);
 MPI_Comm_rank(MPI_COMM_WORLD, &my_rank);
 //now do some parallel stuff
 //.... 
 //finalize to end MPI??
 MPI_Finalize();
)

My code runs normally and I get the expected output, but the problem is that the main function is also Run in a separate process, so the sequence code is executed more than once. I don’t know how many times it runs because I didn’t even call MPI_Init (if I call parallel_function before the main printer, I see multiple printf’s)< /p>

After finishing, how can I run the program in parallel?

Thanks for any response!

Check out this answer.

Short story: MPI_Init and MPI_Finalize do not mark the beginning and end of parallel processing. MPI process Run completely in parallel.