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import math
import os
import time
from cogent3.util import parallel
# the following environment variable is created by PBS on job execution
PBS_NCPUS = os.environ.get("PBS_NCPUS", None)
if PBS_NCPUS is None:
raise RuntimeError("did not get cpu number from environment")
PBS_NCPUS = int(PBS_NCPUS)
def is_prime(n):
# Postprocess the processor MPI rank to check your job got the resources
# you requested
r = parallel.get_rank()
print(f"MPI Rank: {r}")
if n % 2 == 0:
return False
sqrt_n = int(math.floor(math.sqrt(n)))
for i in range(3, sqrt_n + 1, 2):
if n % i == 0:
return False
return True
def main():
# Each worker will evaluate 20 prime numbers. This is just to slow the
# script down!
PRIMES = (
[
112272535095293,
112582705942171,
112272535095293,
115280095190773,
115797848077099,
117450548693743,
993960000099397,
]
* PBS_NCPUS
* 20
)
print(f"MPI World size: {parallel.size}\n")
start = time.time()
result = parallel.map(is_prime, PRIMES, use_mpi=True, max_workers=PBS_NCPUS)
if result != [True] * len(PRIMES):
print(" failed\n")
else:
print(f"{time.time() - start:.2f} seconds\n")
if __name__ == "__main__":
# This block is crucial! See
# https://mpi4py.readthedocs.io/en/stable/mpi4py.futures.html
# for why it needs to be done
main()
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