如何将`Value`实例提交给`ProcessPoolExecution`

Question

我想使用ProcessPoolExecutor的共享状态

代码：

from multiprocessing import Value
from concurrent.futures import ProcessPoolExecutor
def function(times, a):
print('I'm here')
for _ in range(times):
with a.get_lock():
a.value += 1

def main():
a = Value('I', 0, lock=True)
with ProcessPoolExecutor(max_workers=5) as executor:
for i in range(5):
executor.submit(function, 1000000, a)
print("----------------------", a.value)

main()

但它卡住了，甚至没有打印出"我在这里">

Answer 1

您需要将共享变量设置为全局变量，而不是传递参数。

from multiprocessing import Value
from concurrent.futures import ProcessPoolExecutor
def function(times):
print('I'm here')
for _ in range(times):
with a.get_lock():
a.value += 1
def set_global(args):
global a
a = args
def main():
a = Value('I', 0, lock=True)
set_global(a)

with ProcessPoolExecutor(max_workers=5) as executor:
for i in range(5):
executor.submit(function, 1000000)
print("----------------------", a.value)

if __name__ == '__main__':
main()