使用 ProcessPoolExecutor

from concurrent.futures import ProcessPoolExecutor, as_completed

import random

斐波那契数列

当 n 大于 30 时抛出异常

def fib(n):

if n > 30:

raise Exception('can not > 30, now %s' % n)

if n <= 2:

return 1

return fib(n-1) + fib(n-2)

准备数组

nums = [random.randint(0, 33) for _ in range(0, 10)]

'''

[13, 17, 0, 22, 19, 33, 7, 12, 8, 16]

'''

方案一：submit

submit 输出结果按照子进程执行结束的先后顺序，不可控

with ProcessPoolExecutor(max_workers=3) as executor:

futures = {executor.submit(fib, n):n for n in nums}

for f in as_completed(futures):

try:

print('fib(%s) result is %s.' % (futures[f], f.result()))

except Exception as e:

print(e)

'''

fib(13) result is 233.

fib(17) result is 1597.

fib(0) result is 1.

fib(22) result is 17711.

fib(19) result is 4181.

can not > 30, now 33

fib(7) result is 13.

fib(12) result is 144.

fib(8) result is 21.

fib(16) result is 987.

'''

等价写法：

with ProcessPoolExecutor(max_workers=3) as executor:

futures = {}

for n in nums:

job = executor.submit(fib, n)

futures[job] = n

for job in as_completed(futures):

try:

re = job.result()

n = futures[job]

print('fib(%s) result is %s.' % (n, re))

except Exception as e:

print(e)

'''

fib(13) result is 233.

fib(17) result is 1597.

fib(0) result is 1.

fib(22) result is 17711.

can not > 30, now 33

fib(7) result is 13.

fib(19) result is 4181.

fib(8) result is 21.

fib(12) result is 144.

fib(16) result is 987.

'''

方案二：map

map 输出结果按照输入数组的顺序

缺点：某一子进程异常会导致整体中断

with ProcessPoolExecutor(max_workers=3) as executor:

try:

results = executor.map(fib, nums)

for num, result in zip(nums, results):

print('fib(%s) result is %s.' % (num, result))

except Exception as e:

print(e)

'''

fib(13) result is 233.

fib(17) result is 1597.

fib(0) result is 1.

fib(22) result is 17711.

fib(19) result is 4181.

can not > 30, now 33

'''

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