在Python中终止所有线程

Question

我有一个Python脚本，它会不断地对一些IP地址进行ping操作，并把结果打印到屏幕上。 但是我想通过按一个键（最好是按“q”键或者使用“Ctrl+C”）来结束这个脚本，并且希望所有的线程都能被终止。

有什么好的方法可以实现这个呢？我的代码在下面...

import os
import re
import time
import sys
import subprocess
import Queue
import threading

def screen_output(x, y, text):
     sys.stdout.write("\x1b7\x1b[%d;%df%s\x1b8" % (x, y, text))
     sys.stdout.flush()

class pingo:

    def __init__(self,hosts):
        self.q = Queue.Queue()
        self.all_results = {}
        self.hosts = hosts

    def send_ping(self,q,ip):
        self.q.put(self.record_results(ip))

    def record_results(self,ip):
        ping_count = 0

        host_results = {
            "device" : None,
            "sent_count" : 0,
            "success_count": 0,
            "fail_count": 0,
            "failed_perc": 0,
            "curr_status": None
            }


        while True:
            rc = subprocess.call(['ping', '-c', '1', '-W', '1', ip], stdout=open('/dev/null', 'w'), stderr=open('/dev/null', 'w'))
            ping_count += 1

            # update stats

            sent_count = host_results['sent_count']
            success_count = host_results['success_count']
            fail_count = host_results['fail_count']
            failed_perc = host_results['failed_perc']
            curr_status = host_results['curr_status']

            sent_count += 1

            if rc == 0:
                success_count += 1
                curr_status = "Successful Response"
            else:
                fail_count += 1
                curr_status = "Request Timed Out"

            failed_perc =  ( fail_count / sent_count ) * 100

            host_results.update({'failed_perc': failed_perc, 'fail_count': fail_count, 'success_count': success_count, 'curr_status': curr_status, 'sent_count': sent_count})
            time.sleep(0.5)
            self.all_results.update({ip:host_results})
            screen_output(0,0,self.all_results)
        return True

    def go(self):
        for i in self.hosts:
            t = threading.Thread(target=self.send_ping, args = (self.q,i))
            #t.daemon = True
            t.start()

p =  pingo(["8.8.8.8"])
p.go()

编辑：我尝试添加一个全局的ALIVE标志，按照建议的做法，但这仍然无法通过“Ctrl+C”来结束线程。

import sys
import subprocess
import Queue
import threading
import signal

def screen_output(x, y, text):
     sys.stdout.write("\x1b7\x1b[%d;%df%s\x1b8" % (x, y, text))
     sys.stdout.flush()

class pingo:

    def __init__(self,hosts):
        self.q = Queue.Queue()
        self.all_results = {}
        self.hosts = hosts
        self.ALIVE = True

    def signal_handler(self,signal, frame):
        self.ALIVE = False

    def send_ping(self,q,ip):
        self.q.put(self.record_results(ip))

    def record_results(self,ip):
        ping_count = 0

        host_results = {
            "device" : None,
            "sent_count" : 0,
            "success_count": 0,
            "fail_count": 0,
            "failed_perc": 0,
            "curr_status": None
            }


        while self.ALIVE:
            try:
                rc = subprocess.call(['ping', '-c', '1', '-W', '1', ip], stdout=open('/dev/null', 'w'), stderr=open('/dev/null', 'w'))
                ping_count += 1

                # update stats

                sent_count = host_results['sent_count']
                success_count = host_results['success_count']
                fail_count = host_results['fail_count']
                failed_perc = host_results['failed_perc']
                curr_status = host_results['curr_status']

                sent_count += 1

                if rc == 0:
                    success_count += 1
                    curr_status = "Successful Response"
                else:
                    fail_count += 1
                    curr_status = "Request Timed Out"

                failed_perc =  ( fail_count / sent_count ) * 100

                host_results.update({'failed_perc': failed_perc, 'fail_count': fail_count, 'success_count': success_count, 'curr_status': curr_status, 'sent_count': sent_count})
                time.sleep(0.5)
                self.all_results.update({ip:host_results})
                screen_output(0,0,self.all_results)
            except KeyboardInterrupt:
                signal.signal(signal.SIGINT, self.signal_handler)
        return True


    def go(self):
        for i in self.hosts:
            t = threading.Thread(target=self.send_ping, args = (self.q,i))
            #t.daemon = True
            t.start()

p =  pingo(["8.8.8.8"])
p.go()

Answer 1

这是Python中最常见的问题之一。基本上有两种方法可以解决这个问题。

1. （优雅的方法）可以参考@freakish的回答。
2. （懒惰的方法）给所有的工作线程开启“守护线程”标志。可以看看这个问答作为例子：理解Python守护线程

Answer 2

设置一个全局标志 ALIVE（也不一定非得是全局的，你可以用字典或者类的属性），然后把它和 SIGINT 信号绑定，这样在接收到信号时就能改变这个标志：

import signal

ALIVE = True

def signal_handler(signal, frame):
    global ALIVE
    ALIVE = False

signal.signal(signal.SIGINT, signal_handler)

然后只需要把你的循环改成：

def record_results(self,ip):
    # some code
    while ALIVE:
        # some code

这样的话，当收到信号后，它会优雅地退出（会等一段时间后再退出）。