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import math
import os
import time
from collections import Counter
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()
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 r
PRIMES = (
[
112272535095293,
112582705942171,
112272535095293,
115280095190773,
115797848077099,
117450548693743,
993960000099397,
]
* PBS_NCPUS
* 20
)
def main():
print(f"World size: {parallel.SIZE}\n")
# Each worker will evaluate 20 prime numbers. This is just to slow the
# script down!
start = time.time()
result = Counter(
parallel.as_completed(is_prime, PRIMES, use_mpi=True, max_workers=PBS_NCPUS)
)
if sum(result.values()) != len(PRIMES):
print(f" failed: {len(result)} != {len(PRIMES)} : {result=}")
else:
print(
f"Time taken = {time.time() - start:.2f} seconds",
f"CPU rank by number of jobs: {result}",
sep="\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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