如何在Windows上的Python中等待多个子进程，而无需主动等待(轮询)？这样的事情几乎对我有用：

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)"来获取子进程的返回码，因为它们完成了如何在Windows上的Python中实现类似的目的？

解决方案

可能看起来有些矫kill过正，但是，在这里：

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

Twisted具有可在Windows上运行的异步进程生成API。实际上，有几种不同的实现，其中很多都不是很好，但是我们可以在不更改代码的情况下在它们之间进行切换。

Windows上的Twisted将在后台自动执行等待。如果不想使用线程，则必须使用win32 API以避免轮询。像这样的东西：

import win32process
import win32event

# Note: CreateProcess() args are somewhat cryptic, look them up on MSDN
proc1, thread1, pid1, tid1 = win32process.CreateProcess(...)
proc2, thread2, pid2, tid2 = win32process.CreateProcess(...)
thread1.close()
thread2.close()

processes = {proc1: "proc1", proc2: "proc2"}

while processes:
    handles = processes.keys()
    # Note: WaitForMultipleObjects() supports at most 64 processes at a time
    index = win32event.WaitForMultipleObjects(handles, False, win32event.INFINITE)
    finished = handles[index]
    exitcode = win32process.GetExitCodeProcess(finished)
    procname = processes.pop(finished)
    finished.close()
    print "Subprocess %s finished with exit code %d" % (procname, exitcode)

在zseil的答案的基础上，我们可以结合使用子进程和win32 API调用来完成此任务。我使用了直接ctypes，因为我的Python刚好没有安装win32api。我仅以MSYS为例生成sleep.exe，但显然我们可以生成所需的任何进程。我使用OpenProcess()从进程的PID获取HANDLE，然后使用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.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!"