我在Python中进行了多处理，但是我没有任何运气包围着这个话题。基本上我有一个耗时的程序来运行。我需要在1到100的范围内运行它，但是一旦满足我正在寻找的条件，我想中止所有进程。条件是返回值== 90.
这是一个非多进程代码块。任何人都可以给我一个例子，说明他们如何将它转换为多进程函数，其中代码将在＆＃34; 90＆＃34;的条件下退出所有进程。已经满足了？
def Addsomething(i):
SumOfSomething = i + 1
return SumOfSomething
def RunMyProcess():
for i in range(100):
Something = Addsomething(i)
print Something
return
if __name__ == "__main__":
RunMyProcess()
编辑：
我在测试第3版时遇到此错误。知道是什么导致了这个吗？
Exception in thread Thread-3:
Traceback (most recent call last):
File "C:\Python27\lib\threading.py", line 554, in __bootstrap_inner
self.run()
File "C:\Python27\lib\threading.py", line 507, in run
self.__target(*self.__args, **self.__kwargs)
File "C:\Python27\lib\multiprocessing\pool.py", line 379, in _handle_results
cache[job]._set(i, obj)
File "C:\Python27\lib\multiprocessing\pool.py", line 527, in _set
self._callback(self._value)
File "N:\PV\_Proposals\2013\ESS - Clear Sky\01-CODE\MultiTest3.py", line 20, in check_result
pool.terminate()
File "C:\Python27\lib\multiprocessing\pool.py", line 423, in terminate
self._terminate()
File "C:\Python27\lib\multiprocessing\util.py", line 200, in __call__
res = self._callback(*self._args, **self._kwargs)
File "C:\Python27\lib\multiprocessing\pool.py", line 476, in _terminate_pool
result_handler.join(1e100)
File "C:\Python27\lib\threading.py", line 657, in join
raise RuntimeError("cannot join current thread")
RuntimeError: cannot join current thread
答案 0 :(得分：4)
也许这就是你要找的东西？请记住我正在为Python 3编写。上面的print语句是Python 2，在这种情况下，旁注将是使用xrange而不是range。
from argparse import ArgumentParser
from random import random
from subprocess import Popen
from sys import exit
from time import sleep
def add_something(i):
# Sleep to simulate the long calculation
sleep(random() * 30)
return i + 1
def run_my_process():
# Start up all of the processes, pass i as command line argument
# since you have your function in the same file, we'll have to handle that
# inside 'main' below
processes = []
for i in range(100):
processes.append(Popen(['python', 'thisfile.py', str(i)]))
# Wait for your desired process result
# Might want to add a short sleep to the loop
done = False
while not done:
for proc in processes:
returncode = proc.poll()
if returncode == 90:
done = True
break
# Kill any process that are still running
for proc in processes:
if proc.returncode is None:
# Might run into a race condition here,
# so might want to wrap with try block
proc.kill()
if __name__ == '__main__':
# Look for optional i argument here
parser = ArgumentParser()
parser.add_argument('i', type=int, nargs='?')
i = parser.parse_args().i
# If there isn't an i, then run the whole thing
if i is None:
run_my_process()
else:
# Otherwise, run your expensive calculation and return the result
returncode = add_something(i)
print(returncode)
exit(returncode)
修改
这是一个使用多处理模块而不是子进程的更简洁的版本：
from random import random
from multiprocessing import Process
from sys import exit
from time import sleep
def add_something(i):
# Sleep to simulate the long calculation
sleep(random() * 30)
exitcode = i + 1
print(exitcode)
exit(exitcode)
def run_my_process():
# Start up all of the processes
processes = []
for i in range(100):
proc = Process(target=add_something, args=[i])
processes.append(proc)
proc.start()
# Wait for the desired process result
done = False
while not done:
for proc in processes:
if proc.exitcode == 90:
done = True
break
# Kill any processes that are still running
for proc in processes:
if proc.is_alive():
proc.terminate()
if __name__ == '__main__':
run_my_process()
编辑2：
这是最后一个版本，我认为它比其他两个版本要好得多：
from random import random
from multiprocessing import Pool
from time import sleep
def add_something(i):
# Sleep to simulate the long calculation
sleep(random() * 30)
return i + 1
def run_my_process():
# Create a process pool
pool = Pool(100)
# Callback function that checks results and kills the pool
def check_result(result):
print(result)
if result == 90:
pool.terminate()
# Start up all of the processes
for i in range(100):
pool.apply_async(add_something, args=[i], callback=check_result)
pool.close()
pool.join()
if __name__ == '__main__':
run_my_process()