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cimport openmp
from cython.parallel import prange
def check_openmp_num_threads(int n):
"""Run a short parallel section with OpenMP
Return the number of threads that where effectively used by the
OpenMP runtime.
"""
cdef int num_threads = -1
with nogil:
num_threads = inner_openmp_loop(n)
return num_threads
cdef int inner_openmp_loop(int n) nogil:
"""Run a short parallel section with OpenMP
Return the number of threads that where effectively used by the
OpenMP runtime.
This function is expected to run without the GIL and can be called
by an outer OpenMP / prange loop written in Cython in another file.
"""
cdef long n_sum = 0
cdef int i, num_threads
for i in prange(n):
num_threads = openmp.omp_get_num_threads()
n_sum += i
if n_sum != (n - 1) * n / 2:
# error
return -1
return num_threads
|
