Question

当我尝试运行来自documantaions的简单操作时，例如： https://docs.python.org/3.4/library/multiprocessing.html?highlight=process

from multiprocessing import Pool

def f(x):
    return x*x

if __name__ == '__main__':
    with Pool(5) as p:
        print(p.map(f, [1, 2, 3]))

它无限期地运行代码。我试图添加close和join，并试图获取过程的ID，但没有任何效果。好像它一遍又一遍地循环池，无法执行它。怎么了？

from datetime
import datetime from datetime
import date
import os
import time
from multiprocessing import Pool
def y(z):
    print(f'Process {os.getpid()} working record {z}')
    time.sleep(1)
    q = z*2
    print(f'Process {os.getpid()} done record {q}')
    return(q)

with Pool(2) as p:
    result = p.map(y, [1, 2, 3])
    p.close()
    p.join()
end_time = datetime.now() 
print('Duration: {}'.format(end_time - start_time))

＃＃＃＃＃＃错误

Process SpawnPoolWorker-1:
Process SpawnPoolWorker-2:
Traceback (most recent call last):
  File "C:\Users\a.ovchinnikov\AppData\Local\Continuum\anaconda3\lib\multiprocessing\process.py", line 297, in _bootstrap
    self.run()
  File "C:\Users\a.ovchinnikov\AppData\Local\Continuum\anaconda3\lib\multiprocessing\process.py", line 99, in run
    self._target(*self._args, **self._kwargs)
  File "C:\Users\a.ovchinnikov\AppData\Local\Continuum\anaconda3\lib\multiprocessing\pool.py", line 110, in worker
    task = get()
  File "C:\Users\a.ovchinnikov\AppData\Local\Continuum\anaconda3\lib\multiprocessing\queues.py", line 354, in get
    return _ForkingPickler.loads(res)
AttributeError: Can't get attribute 'y' on <module '__main__' (built-in)>
Traceback (most recent call last):
  File "C:\Users\a.ovchinnikov\AppData\Local\Continuum\anaconda3\lib\multiprocessing\process.py", line 297, in _bootstrap
    self.run()
  File "C:\Users\a.ovchinnikov\AppData\Local\Continuum\anaconda3\lib\multiprocessing\process.py", line 99, in run
    self._target(*self._args, **self._kwargs)
  File "C:\Users\a.ovchinnikov\AppData\Local\Continuum\anaconda3\lib\multiprocessing\pool.py", line 110, in worker
    task = get()
  File "C:\Users\a.ovchinnikov\AppData\Local\Continuum\anaconda3\lib\multiprocessing\queues.py", line 354, in get
    return _ForkingPickler.loads(res)
AttributeError: Can't get attribute 'y' on <module '__main__' (built-in)>
Process SpawnPoolWorker-3:
Traceback (most recent call last):
  File "C:\Users\a.ovchinnikov\AppData\Local\Continuum\anaconda3\lib\multiprocessing\process.py", line 297, in _bootstrap
    self.run()
  File "C:\Users\a.ovchinnikov\AppData\Local\Continuum\anaconda3\lib\multiprocessing\process.py", line 99, in run
    self._target(*self._args, **self._kwargs)
  File "C:\Users\a.ovchinnikov\AppData\Local\Continuum\anaconda3\lib\multiprocessing\pool.py", line 110, in worker
    task = get()
  File "C:\Users\a.ovchinnikov\AppData\Local\Continuum\anaconda3\lib\multiprocessing\queues.py", line 354, in get
    return _ForkingPickler.loads(res)
AttributeError: Can't get attribute 'y' on <module '__main__' (built-in)>

Answer 1

在修复了第二个语法错误（似乎只是复制粘贴问题）后，您的两个代码示例都在我的机器上的python3中正常运行。（请参阅下面的编辑代码。）也许您的计算机上配置错误，或者您没有使用正确的命令来运行它们？您能够成功运行其他python程序吗？

from datetime import datetime
from datetime import date
import os
import time
from multiprocessing import Pool
def y(z):
    print(f'Process {os.getpid()} working record {z}')
    time.sleep(1)
    q = z*2
    print(f'Process {os.getpid()} done record {q}')
    return(q)

start_time = datetime.now() 
with Pool(2) as p:
    result = p.map(y, [1, 2, 3])
    p.close()
    p.join()

end_time = datetime.now() 
print('Duration: {}'.format(end_time - start_time))

无限多处理池

1 个答案: