线程程序不会退出

Question

我正在编写一个程序，该程序不断检查某些IP地址是否连接到网络。如果是，什么也不会发生。如果它们在一段时间内没有连接，则会触发一个操作。据我所知，我的脚本可以按预期工作，但当我尝试使用ctrl+c退出它时，它根本不会停止。我想这和我使用的线程有关，但我不知道它到底是什么。这是我迄今为止的代码：

import os
import time
from threading import Timer, Thread
import json
with open("ip_adresses.json", "r") as f:
ip_adresses_dict = json.load(f)

def timeout():
print("ACTION IS TRIGGERED")

# dummy Timer thread
print("dummy timer created")
t = Timer(999999999, timeout)
t.daemon = True
try:
while True:
ip_adress_reachable = []
for key, value in ip_adresses_dict.items():
if os.system(f"ping -c 1 -W 1 {value} > /dev/null") is 0:  # this means its reachable
ip_adress_reachable.append(True)
else:
ip_adress_reachable.append(False)
print(ip_adress_reachable)
# if no ip adresses are reachable and no timer running, start a timer.
if any(ip_adress_reachable) == False and t.is_alive() == False:
print("starting a new thread")
t = Timer(15, timeout)
t.daemon = True
t.start()
# If in the meantime ip adress gets reachable cancel the timer.
elif any(ip_adress_reachable) == True and t.is_alive() == True:
# cancel the timer
print("timer was canceled")
t.cancel()

except KeyboardInterrupt:
print("quitting")
t.join(1)

我有点迷路了，因为我认为deamon线程会在主循环完成后(即在我按下ctr+c后(停止

如果有人能帮我，我将不胜感激。

Answer 1

经过测试，我发现所有的问题都使os.system()捕获Ctrl+C以停止进程在os.system()-ping-中运行，并且它没有将这些信息发送到Python。

如果运行ping的时间更长，则跳过/dev/null

os.system(f"ping -c 5 -W 1 {value}")

然后你会看到Ctrl+C停止ping

如果我使用subprocess，那么我就没有这个问题。

subprocess.call(f"ping -c 1 -W 1 {value} > /dev/null", shell=True)

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我在Linux Mint 20上测试的代码(基于Ubuntu 20.04(

#import os
import time
from threading import Timer, Thread
#import json
import subprocess
#with open("ip_adresses.json", "r") as f:
#    ip_adresses_dict = json.load(f)
ip_adresses_dict = {
'x': '192.168.0.1',
'y': '192.168.0.2',
'z': '192.168.0.3',       
}
def timeout():
print("ACTION IS TRIGGERED")
# dummy Timer thread
print("dummy timer created")
t = Timer(999999999, timeout)
t.daemon = True
try:
while True:
ip_adress_reachable = []

for key, value in ip_adresses_dict.items():
print('[DEBUG] start process')
#result = os.system(f"ping -c 1 -W 1 {value} > /dev/null")
#result = os.system(f"ping -c 5 -W 1 {value}")
result = subprocess.call(f"ping -c 1 -W 1 {value} > /dev/null", shell=True)
print('[DEBUG] end process')
ip_adress_reachable.append( result == 0 )

print(ip_adress_reachable)
# if no ip adresses are reachable and no timer running, start a timer.
if any(ip_adress_reachable) is False and t.is_alive() is False:
print("starting a new thread")
t = Timer(15, timeout)
t.daemon = True
t.start()
# If in the meantime ip adress gets reachable cancel the timer.
elif any(ip_adress_reachable) is True and t.is_alive() is True:
# cancel the timer
print("timer was canceled")
t.cancel()
except KeyboardInterrupt:
print("quitting")
if t.is_alive():
t.join(1)

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