renumbering chapters >= 19

20-futures/primes/proc_pool.py

@@ -0,0 +1,50 @@
+#!/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[]
+import sys
+from concurrent import futures  # <1>
+from time import perf_counter
+from typing import NamedTuple
+
+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(f'Total time: {time:.2f}s')
+
+if __name__ == '__main__':
+    main()
+# end::PRIMES_POOL[]