OMP_GET_THREAD_NUM
Purpose:
Returns the thread number of the thread, within the team, making this call. This number will be between 0 and OMP_GET_NUM_THREADS-1. The master thread of the team is thread 0.
Format:
Fortran
INTEGER FUNCTION OMP_GET_THREAD_NUM()
C/C++
#include <omp.h>
int omp_get_thread_num(void)
Notes & Restrictions:
If called from a nested parallel region, or a serial region, this function will return 0.
Examples in Fortran:determining the number of threads in a parallel region
- Example 1 is the correct way to determine the number of threads in a parallel region.
- Example 2 is incorrect - the TID variable must be PRIVATE
- Example 3 is incorrect - the OMP_GET_THREAD_NUM call is outside the parallel region
Example 1: Correct
PROGRAM HELLO
INTEGER TID, OMP_GET_THREAD_NUM
!$OMP PARALLEL PRIVATE(TID)
TID = OMP_GET_THREAD_NUM()
PRINT *, 'Hello World from thread = ', TID
...
!$OMP END PARALLEL
END
Example 2: Incorrect
PROGRAM HELLO
INTEGER TID, OMP_GET_THREAD_NUM
!$OMP PARALLEL
TID = OMP_GET_THREAD_NUM()
PRINT *, 'Hello World from thread = ', TID
...
!$OMP END PARALLEL
END
Example 3: Incorrect
PROGRAM HELLO
INTEGER TID, OMP_GET_THREAD_NUM
TID = OMP_GET_THREAD_NUM()
PRINT *, 'Hello World from thread = ', TID
!$OMP PARALLEL
...
!$OMP END PARALLEL
END
