爲什麼Popen子進程不會死？

Question

我正在啓動一個Popen的子過程，我期望它完成退出。然而，這個過程不僅不能退出，而且發送sigkill仍然會使它活着！下面是一個腳本演示：

from subprocess import Popen 
import os 
import time 
import signal 

command = ["python","--version"] 

process = Popen(command) 
pid = process.pid 

time.sleep(5) #ample time to finish 

print pid 

print "Sending sigkill" 
os.kill(pid,signal.SIGKILL) 

try: 
    #Kill with signal 0 just checks whether process exists 
    os.kill(pid,0) 
    print "Process still alive immediately after (not so bad...)!" 
except Exception as e: 
    print "Succeeded in terminating child quickly!" 

time.sleep(20) #Give it ample time to die 

#Kill with signal 0 just checks whether process exists 
try: 
    os.kill(pid,0) 
    print "Process still alive! That's bad!" 
except Exception as e: 
    print "Succeeded in terminating child!" 

對於我來說，這個打印：

77881 
Python 2.7.10 
Sending sigkill 
Process still alive immediately after (not so bad...)! 
Process still alive! That's bad! 

這不僅可以腳本驗證孩子還活着就應該已經完成​​之後，但我可以用ps在打印的進程ID上看到它仍然存在。奇怪的是，ps列出進程名稱爲(Python)（注意括號）。

Answer 1

您需要撥打process.wait()或使用signal.signal(signal.SIGCHLD, signal.SIG_IGN)一次表明您不打算等待任何孩子。前者是便攜式的;後者只適用於Unix（但是是POSIX-standard）。如果你沒有做這些事情，那麼在Unix上，這個過程將作爲一個殭屍來掛起，而Windows has a similar behavior if you keep the process handle open。