我有一个在Python3.8中运行的简单示例代码，它打开了在Python2.7中执行的subprocess(利用多处理(。
在Windows 10中，我的代码的行为就是我的意图。Python2池在哪里运行并相应地打印到stdout。当池在main.py上写入时，CCD_6几乎立即读取stdout
不幸的是，我在Linux(Ubuntu 20.04.1 LTS(上看到了不同的结果。看来，在Linux中，在整个池完成之前，我不会得到任何东西。
如何使代码在Linux中也能正常工作？
请参阅下面的简单示例代码和我得到的输出。
主要.py
import subprocess
import datetime
import tempfile
import os
def get_time():
return datetime.datetime.now()
class ProcReader():
def __init__(self, python_file, temp=None, wait=False):
self.proc = subprocess.Popen(['python2', python_file], stdout=subprocess.PIPE)
def __iter__(self):
return self
def __next__(self):
while True:
line = self.proc.stdout.readline()
if not line:
raise StopIteration
return line
if __name__ == "__main__":
r1 = ProcReader("p2.py")
for l1 in r1:
print("Main reading at: {} for {}".format(get_time(), l1))
p2.py
import time
import multiprocessing as mp
from multiprocessing import freeze_support
import datetime
def get_time():
return datetime.datetime.now()
def f1(name):
for x in range(2):
time.sleep(1)
print("{} Job#: {} from f1".format(get_time(), name))
def f2(name):
for x in range(2):
time.sleep(2)
print("{} Job#: {} from f2".format(get_time(), name))
if __name__ == '__main__':
freeze_support()
pool = mp.Pool(2)
tasks = ["1", "2", "3", "4", "5", "6", "7"]
for i, task in enumerate(tasks):
if i%2:
pool.apply_async(f2, args=(task,))
else:
pool.apply_async(f1, args=(task,))
pool.close()
pool.join()
Windows的输出：
Main reading at: 2020-09-24 15:28:19.044626 for b'2020-09-24 15:28:19.044000 Job#: 1 from f1n'
Main reading at: 2020-09-24 15:28:20.045454 for b'2020-09-24 15:28:20.045000 Job#: 1 from f1n'
Main reading at: 2020-09-24 15:28:20.046711 for b'2020-09-24 15:28:20.046000 Job#: 2 from f2n'
Main reading at: 2020-09-24 15:28:21.045510 for b'2020-09-24 15:28:21.045000 Job#: 3 from f1n'
Main reading at: 2020-09-24 15:28:22.046334 for b'2020-09-24 15:28:22.046000 Job#: 3 from f1n'
Main reading at: 2020-09-24 15:28:22.047368 for b'2020-09-24 15:28:22.047000 Job#: 2 from f2n'
Main reading at: 2020-09-24 15:28:23.047519 for b'2020-09-24 15:28:23.047000 Job#: 5 from f1n'
Main reading at: 2020-09-24 15:28:24.046356 for b'2020-09-24 15:28:24.046000 Job#: 4 from f2n'
Main reading at: 2020-09-24 15:28:24.048356 for b'2020-09-24 15:28:24.048000 Job#: 5 from f1n'
Main reading at: 2020-09-24 15:28:26.047307 for b'2020-09-24 15:28:26.047000 Job#: 4 from f2n'
Main reading at: 2020-09-24 15:28:26.049168 for b'2020-09-24 15:28:26.049000 Job#: 6 from f2n'
Main reading at: 2020-09-24 15:28:27.047897 for b'2020-09-24 15:28:27.047000 Job#: 7 from f1n'
Main reading at: 2020-09-24 15:28:28.048337 for b'2020-09-24 15:28:28.048000 Job#: 7 from f1n'
Main reading at: 2020-09-24 15:28:28.049367 for b'2020-09-24 15:28:28.049000 Job#: 6 from f2n'
Linux输出：
Main reading at: 2020-09-24 19:28:45.972346 for b'2020-09-24 19:28:36.932473 Job#: 1 from f1n'
Main reading at: 2020-09-24 19:28:45.972559 for b'2020-09-24 19:28:37.933594 Job#: 1 from f1n'
Main reading at: 2020-09-24 19:28:45.972585 for b'2020-09-24 19:28:38.935255 Job#: 3 from f1n'
Main reading at: 2020-09-24 19:28:45.972597 for b'2020-09-24 19:28:39.936297 Job#: 3 from f1n'
Main reading at: 2020-09-24 19:28:45.972685 for b'2020-09-24 19:28:40.937666 Job#: 5 from f1n'
Main reading at: 2020-09-24 19:28:45.972711 for b'2020-09-24 19:28:41.938629 Job#: 5 from f1n'
Main reading at: 2020-09-24 19:28:45.972724 for b'2020-09-24 19:28:43.941109 Job#: 6 from f2n'
Main reading at: 2020-09-24 19:28:45.972735 for b'2020-09-24 19:28:45.943310 Job#: 6 from f2n'
Main reading at: 2020-09-24 19:28:45.973115 for b'2020-09-24 19:28:37.933317 Job#: 2 from f2n'
Main reading at: 2020-09-24 19:28:45.973139 for b'2020-09-24 19:28:39.935938 Job#: 2 from f2n'
Main reading at: 2020-09-24 19:28:45.973149 for b'2020-09-24 19:28:41.938587 Job#: 4 from f2n'
Main reading at: 2020-09-24 19:28:45.973157 for b'2020-09-24 19:28:43.941109 Job#: 4 from f2n'
Main reading at: 2020-09-24 19:28:45.973165 for b'2020-09-24 19:28:44.942306 Job#: 7 from f1n'
Main reading at: 2020-09-24 19:28:45.973173 for b'2020-09-24 19:28:45.943503 Job#: 7 from f1n'
请忽略时间，因为时钟不同，但正如您所看到的，在Windows中，main.py在python2池中写入后立即获取时间，但对于linux，main.py中的所有内容只有在所有作业完成时才会写入。我不太关心作业完成的顺序，我真的只希望main.py在Python2池中写入stdout后立即获得它。
Linux上的stdout是缓冲的，而多处理上的CCD14则不刷新，因为进程不控制终端。
sys.stdout的Monkey补丁在这里很有用
import sys,os
unbuffered = os.fdopen(sys.stdout.fileno(), 'w', 0)
sys.stdout = unbuffered
或者您可能需要在每次print()后致电sys.stdout.flush()