1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
|
import math
import sys
from mpi4py.futures import MPIPoolExecutor, get_comm_workers, wait
def compute_pi(n):
comm = get_comm_workers()
comm.barrier()
n = comm.bcast(n, root=0)
h = 1.0 / n
s = 0.0
for i in range(comm.rank + 1, n + 1, comm.size):
x = h * (i - 0.5)
s += 4.0 / (1.0 + x**2)
pi = comm.allreduce(s * h)
return pi
def main():
try:
n = int(sys.argv[1])
except IndexError:
n = 256
try:
P = int(sys.argv[2])
except IndexError:
P = 5
with MPIPoolExecutor(P) as executor:
P = executor.num_workers
fs = [executor.submit(compute_pi, n) for _ in range(P)]
wait(fs)
pi = fs[0].result()
print(
f"pi: {pi:.15f}, error: {abs(pi - math.pi):.3e}",
f"({n:d} intervals, {P:d} workers)",
)
if __name__ == "__main__":
main()
|
