如何在Python中调用具有指定时间限制的系统命令？

参见英文答案 > How to terminate a python subprocess launched with shell=True????????????????????????????????????10个
我正在创建一个调用一些系统命令的Python应用程序.但是,如果它们花费太多时间(比如10s),我希望它终止这些命令.我尝试使用一些子过程自己做这件事 – 没有太大的成功.在stackoverflow上搜索后,我发现了以下问题：
Using module ‘subprocess’ with timeout

它有一个答案,几乎对我有用 – 问题是,当进程被“终止”时,它实际上不是 – 实际上,即使我的脚本完成后,该进程仍然在后台运行.当然这不是一个理想的效果,但我找不到解决方法.有没有一个解决这个问题的优先解决方案？

来自上述答案的代码(不良代码)供参考：

import subprocess,threading

class Command(object):
    def __init__(self,cmd):
        self.cmd = cmd
        self.process = None

    def run(self,timeout):
        def target():
            print 'Thread started'
            self.process = subprocess.Popen(self.cmd,shell=True)
            self.process.communicate()
            print 'Thread finished'

        thread = threading.Thread(target=target)
        thread.start()

        thread.join(timeout)
        if thread.is_alive():
            print 'Terminating process'
            self.process.terminate()
            thread.join()
        print self.process.returncode

command = Command("echo 'Process started'; sleep 2; echo 'Process finished'")
command.run(timeout=3)
command.run(timeout=1)

os.killpg(self.process.pid,signal.SIGTERM)

self.process.terminate()

import subprocess,threading
import os,signal
class Command(object):
    def __init__(self,shell=True,preexec_fn=os.setsid)
            self.process.communicate()
            print 'Thread finished'

        thread = threading.Thread(target=target)
        thread.start()

        thread.join(timeout)
        if thread.is_alive():
            print 'Terminating process'
            os.killpg(self.process.pid,signal.SIGTERM)
            thread.join()
        print self.process.returncode

command = Command("echo 'Process started'; sleep 2; echo 'Process finished'")
command.run(timeout=3)
command.run(timeout=1)