python signal信号
让chatgpt达芬奇帮忙写代码
问：
帮我写一段python脚本，要求注册信号，当接收到信号值15后，程序正常退出
答：
import signal
import sysdef signal_handler(signal_num, frame):if signal_num == 15:print("Received signal: %s, program exits normally" % signal_num)sys.exit()# register signal
signal.signal(15, signal_handler)print("Waiting for signal 15...")
while True:pass
这跑起来稳稳的。。。
20230816
文章目录
- Python Signal 信号处理
- 什么是Signal？
- Python中的Signal模块
- 使用Signal模块处理超时
- 信号和多线程
- 总结
- 参考资料
- 投票
Python Signal 信号处理
在本文中，我们将深入探讨Python的signal模块，这是一个提供了Unix风格信号处理功能的模块。Python signal模块允许定义在接收到操作系统发送的信号时执行的自定义行为。例如，可以设置程序在接收到“SIGINT”信号（通常由用户按下Ctrl+C产生）时应如何响应。
什么是Signal？
在计算机科学中，一个信号（signal）是一种软件中断，它向一个进程发送信息，告知该进程发生了某些情况。Unix和Linux系统支持多种信号，比如SIGINT、SIGTERM等。每个信号都有默认的行为，比如终止进程或忽略信号。但是，大多数信号都可以被捕获并由程序定义自己的处理方式。
Python中的Signal模块
Python的signal模块提供了对信号处理的接口。其主要函数是signal.signal()，它定义了一个信号的处理器，当接收到特定的信号时，会调用该处理器。
以下是使用signal模块设置信号处理器的基本方法：
import signal
import os
import timedef handler(signum, frame):print('Signal handler called with signal', signum)# Set the signal handler
signal.signal(signal.SIGINT, handler)while True:time.sleep(1)
上述代码首先导入了所需的模块，然后定义了一个名为handler的函数，该函数打印出接收到的信号编号。然后，使用signal.signal()函数设置了当接收到SIGINT信号时调用handler函数。最后，程序进入一个无限循环，除非接收到SIGINT信号（通过按下Ctrl+C）才会跳出循环。
使用Signal模块处理超时
Python的signal模块还可以用来处理超时情况。例如，如果有一个函数可能会运行很长时间，并且希望在一定时间后停止运行该函数，就可以使用signal模块实现。
下面是一个例子，演示如何使用signal模块设置超时：
import signaldef handler(signum, frame):raise Exception("Timeout!")signal.signal(signal.SIGALRM, handler)
signal.alarm(5)try:# This function may run for an indeterminate amount of timelong_running_function()
except Exception as e:print(e)
在这个例子中，signal.alarm(5)设定了一个5秒的计时器，当时间到达时，操作系统会发送一个SIGALRM信号。该信号被我们预设的handler捕获，抛出一个异常，表示函数运行超时。
信号和多线程
需要注意的是，Python的信号模块不适合用于多线程环境，因为只有主线程才能捕获到信号。这意味着，如果创建了一个新的线程并希望在这个线程中处理信号，那么这个信号处理程序可能永远不会被调用。
import signal
import threading
import timedef handler(signum, frame):print('Signal handler called with signal', signum)signal.signal(signal.SIGINT, handler)def run():while True:time.sleep(1)t = threading.Thread(target=run)
t.start()
t.join()
在上述代码中，尽管我们已经设置了一个信号处理器，但是如果按下Ctrl+C，信号处理器并不会被调用，因为这个信号被发送到了主线程，而不是新创建的线程。
总结
Python的signal模块提供了强大的信号处理功能，使得我们可以自定义程序在接收到特定信号时的行为。然而，也需要注意到它在多线程环境中的局限性。
参考资料
- Python official documentation - Signal
- Python and Unix signals
投票
在您阅读了本篇关于Python signal模块的文章之后，您是否觉得这是一个值得在日常编程中使用的工具？
- 是的，我觉得signal模块非常有用。
- 不确定，我需要更多时间去理解和尝试。
- 不，我认为这个模块的用处有限。
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