psutil是一个跨平台库(http://pythonhosted.org/psutil/)能够轻松实现获取系统运行的进程和系统利用率（包括CPU、内存、磁盘、网络等）信息。它主要用来做系统监控，性能分析，进程管理。它实现了同等命令行工具提供的功能，如ps、top、lsof、netstat、ifconfig、who、df、kill、free、nice、ionice、iostat、iotop、uptime、pidof、tty、taskset、pmap等。目前支持32位和64位的Linux、Windows、OS X、FreeBSD和Sun Solaris等操作系统.
Kill process tree
```
import os
import signal
import psutil
def kill_proc_tree(pid, sig=signal.SIGTERM, include_parent=True,
timeout=None, on_terminate=None):
"""Kill a process tree (including grandchildren) with signal
"sig" and return a (gone, still_alive) tuple.
"on_terminate", if specified, is a callabck function which is
called as soon as a child terminates.
"""
assert pid !=
os.getpid(), "won't kill myself"
parent = psutil.Process(pid)
children = parent.children(recursive=True)
if include_parent:
children.append(parent)
for p in children:
p.send_signal(sig)
gone, alive = psutil.wait_procs(children, timeout=timeout,
callback=on_terminate)
return (gone, alive)
```
