的Python multiprocessing.Pool是在Windows

奇怪我有一個超級簡單的Python腳本如下的Python multiprocessing.Pool是在Windows

import multiprocessing 
from multiprocessing import Pool 

print "CPUs: " + str(multiprocessing.cpu_count()) 
convertPool = Pool(multiprocessing.cpu_count())

在Linux定義這似乎表現爲我的預計，隨着該計劃剛剛起步，然後打印出核心數量，然後退出。然而，在Windows上，這個程序將繼續調用新的python命令並打印出「CPU：4」（我有4個內核）並且永不停止運行，並且最終會終止該命令。有人能解釋一下這裏發生了什麼嗎？

感謝

編輯：我現在有下面的程序仍然不工作，我期望

import sys 
import os 
import subprocess 
from subprocess import Popen, PIPE 
from threading import Thread 
import multiprocessing 
from multiprocessing import Pool, freeze_support 

try: 
    from Queue import Queue, Empty 
except ImportError: 
    from queue import Queue, Empty # python 3.x 

ON_POSIX = "posix" in sys.builtin_module_names 

def myPrint(line, logWriter): 
    if logWriter is None: 
     # This will print without a newline, cause the process 
     # has its own newlines 
     sys.stdout.write(line) 
    else: 
     logWriter.write(line.strip()) 
     logWriter.write("\n") 
     logWriter.flush() 

# This is gotten from http://stackoverflow.com/questions/375427/non-blocking-read-on-a-subprocess-pipe-in-python 
def executeCommand(cmd, logWriter): 
    myPrint(cmd + "\n", logWriter) 
    p = Popen(cmd, stdout=PIPE, bufsize=4096, close_fds=ON_POSIX, shell=True) 
    q = Queue() 
    t = Thread(target=enqueue_output, args=(p.stdout, q)) 
    t.daemon = True # thread dies with the program 
    t.start() 

    # read line without blocking 
    while t.isAlive() or not q.empty(): 
     try: 
      line = q.get_nowait() # or q.get(timeout=.1) 
     except Empty: 
      pass # Do nothing 
     else: # If there is a line, then print it 
      if logWriter is not None: 
       myPrint(line, logWriter) 
     # Sleep to prevent python from using too much cpu 
     time.sleep(0.05) 

if __name__ == "__main__": 
    freeze_support() 
    convertPool = Pool(multiprocessing.cpu_count()) 
    # Now let's smooth and threshold all the masks 
    for foo in bar: 
     threshSmoothCmd = "ConvertImage.exe -i " + foo + " -o " + foo 
     myPrint(threshSmoothCmd + "\n", None) 
     convertPool.apply_async(executeCommand,(threshSmoothCmd, None,)) 

    convertPool.close() 
    convertPool.join() 
print "Finished processing"

ConvertImage.exe是一個可執行文件我寫我自己foo和酒吧都只是佔位符。在Linux上，這將啓動Multiprocessing.cpu_count（）數量的ConvertImage.exe進程，並在所有ConvertImage.exe進程完成後打印完成的進程。在Windows上，立即啓動len（bar）ConvertImage.exe進程，然後立即打印完成的處理並退出。我如何讓Windows版本像Linux版本一樣運行？

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2012-07-16 Jon

包括'if __name__ =='__main __「：'使這個工作。這在'multiprocessing'文檔中有介紹。 – 2012-07-16 17:09:52

另外請注意，在我看來，它不是'multiprocessing.Pool'，這很奇怪。奇怪的是Windows缺少'fork（）'。 – 2012-07-16 17:10:38

[python3.x multiprocessing cycling without possible if if __name__ =='__main__'：「]的可能重複（http://stackoverflow.com/questions/11501048/python3-x-multiprocessing-cycling-without-if-name-main ） – 2012-07-16 17:13:25

我弄明白了，它工作正常，我的示例程序發佈錯誤，因爲我忘記了一些導入並導致描述的行爲。在得到所有導入後，這個例子在Windows和Linux上運行良好。

來源

2012-07-16 18:07:28 Jon

的Python multiprocessing.Pool是在Windows

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