Windows上的Python-如何等待多个子进程？

Question

如何在Windows上的Python中等待多个子进程，而不进行活动等待（polling）？像这样的东西几乎对我有效：

proc1 = subprocess.Popen(['python','mytest.py'])
proc2 = subprocess.Popen(['python','mytest.py'])    
proc1.wait()
print "1 finished"
proc2.wait()
print "2 finished"

问题是，当proc2在proc1之前完成时，父进程仍将等待proc1。在Unix上，人们会在循环中使用waitpid(0)来获取子进程完成时的返回代码-如何在Windows上的Python中实现这样的功能？

Answer 1

看起来有点过头了，但是，这里有：

import Queue, thread, subprocess

results= Queue.Queue()
def process_waiter(popen, description, que):
    try: popen.wait()
    finally: que.put( (description, popen.returncode) )
process_count= 0

proc1= subprocess.Popen( ['python', 'mytest.py'] )
thread.start_new_thread(process_waiter,
    (proc1, "1 finished", results))
process_count+= 1

proc2= subprocess.Popen( ['python', 'mytest.py'] )
thread.start_new_thread(process_waiter,
    (proc2, "2 finished", results))
process_count+= 1

# etc

while process_count > 0:
    description, rc= results.get()
    print "job", description, "ended with rc =", rc
    process_count-= 1

Answer 2

基于zseil的答案，您可以通过混合使用子进程和win32 API调用来实现这一点。我使用了直接的ctypes，因为我的Python没有安装win32api。我只是从MSYS中生成sleep.exe作为一个例子，但是很明显你可以生成任何你喜欢的进程。我使用OpenProcess（）从进程的PID中获取一个句柄，然后WaitForMultipleObjects等待任何进程完成。

import ctypes, subprocess
from random import randint
SYNCHRONIZE=0x00100000
INFINITE = -1
numprocs = 5
handles = {}

for i in xrange(numprocs):
    sleeptime = randint(5,10)
    p = subprocess.Popen([r"c:\msys\1.0\bin\sleep.exe", str(sleeptime)], stdin=subprocess.PIPE, stdout=subprocess.PIPE, stderr=subprocess.PIPE, shell=False)
    h = ctypes.windll.kernel32.OpenProcess(SYNCHRONIZE, False, p.pid)
    handles[h] = p.pid
    print "Spawned Process %d" % p.pid

while len(handles) > 0:
    print "Waiting for %d children..." % len(handles)
    arrtype = ctypes.c_long * len(handles)
    handle_array = arrtype(*handles.keys())
    ret = ctypes.windll.kernel32.WaitForMultipleObjects(len(handle_array), handle_array, False, INFINITE)
    h = handle_array[ret]
    ctypes.windll.kernel32.CloseHandle(h)
    print "Process %d done" % handles[h]
    del handles[h]
print "All done!"

Answer 3

Twisted有一个在Windows上工作的asynchronous process-spawning API。实际上有几个不同的实现，其中许多不是很好，但您可以在它们之间切换，而不必更改代码。