ch21 examples

21-futures/primes/primes.py

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+#!/usr/bin/env python3
+
+import math
+
+
+PRIME_FIXTURE = [
+    (2, True),
+    (142702110479723, True),
+    (299593572317531, True),
+    (3333333333333301, True),
+    (3333333333333333, False),
+    (3333335652092209, False),
+    (4444444444444423, True),
+    (4444444444444444, False),
+    (4444444488888889, False),
+    (5555553133149889, False),
+    (5555555555555503, True),
+    (5555555555555555, False),
+    (6666666666666666, False),
+    (6666666666666719, True),
+    (6666667141414921, False),
+    (7777777536340681, False),
+    (7777777777777753, True),
+    (7777777777777777, False),
+    (9999999999999917, True),
+    (9999999999999999, False),
+]
+
+NUMBERS = [n for n, _ in PRIME_FIXTURE]
+
+# tag::IS_PRIME[]
+def is_prime(n: int) -> bool:
+    if n < 2:
+        return False
+    if n == 2:
+        return True
+    if n % 2 == 0:
+        return False
+
+    root = math.isqrt(n)
+    for i in range(3, root + 1, 2):
+        if n % i == 0:
+            return False
+    return True
+# end::IS_PRIME[]
+
+if __name__ == '__main__':
+
+    for n, prime in PRIME_FIXTURE:
+        prime_res = is_prime(n)
+        assert prime_res == prime
+        print(n, prime)

21-futures/primes/proc_pool.py

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+#!/usr/bin/env python3
+
+"""
+proc_pool.py: a version of the proc.py example from chapter 20,
+but using `concurrent.futures.ProcessPoolExecutor`.
+"""
+
+# tag::PRIMES_POOL[]
+from time import perf_counter
+from typing import NamedTuple
+from concurrent import futures  # <1>
+import sys
+
+from primes import is_prime, NUMBERS
+
+class PrimeResult(NamedTuple):  # <2>
+    n: int
+    flag: bool
+    elapsed: float
+
+def check(n: int) -> PrimeResult:
+    t0 = perf_counter()
+    res = is_prime(n)
+    return PrimeResult(n, res, perf_counter() - t0)
+
+def main() -> None:
+    if len(sys.argv) < 2:
+        workers = None      # <3>
+    else:
+        workers = int(sys.argv[1])
+
+    executor = futures.ProcessPoolExecutor(workers)  # <4>
+    actual_workers = executor._max_workers  # type: ignore  # <5>
+
+    print(f'Checking {len(NUMBERS)} numbers with {actual_workers} processes:')
+
+    t0 = perf_counter()
+
+    numbers = sorted(NUMBERS, reverse=True)  # <6>
+    with executor:  # <7>
+        for n, prime, elapsed in executor.map(check, numbers):  # <8>
+            label = 'P' if prime else ' '
+            print(f'{n:16}  {label} {elapsed:9.6f}s')
+
+    time = perf_counter() - t0
+    print('Total time:', f'{time:0.2f}s')
+
+if __name__ == '__main__':
+    main()
+# end::PRIMES_POOL[]