如何从 python 程序发送信号？

Question

我有这个监听 USR1 信号的代码

import signal
import os
import time

def receive_signal(signum, stack):
    print 'Received:', signum

signal.signal(signal.SIGUSR1, receive_signal)
signal.signal(signal.SIGUSR2, receive_signal)

print 'My PID is:', os.getpid()

while True:
    print 'Waiting...'
    time.sleep(3)

当我使用 kill -USR1 pid 发送信号时，这有效

但是如何从上述 python 脚本中发送相同的信号，以便在 10 秒后自动发送 USR1 并接收它，而无需我打开两个终端来检查它？

Answer 1

你可以使用os.kill():

os.kill(os.getpid(), signal.SIGUSR1)

将它放在代码中要从中发送信号的任何位置。

Answer 2

如果您愿意捕捉SIGALRM 而不是SIGUSR1，请尝试：

signal.alarm(10)

否则，您将需要启动另一个线程：

import time, os, signal, threading
pid = os.getpid()
thread = threading.Thread(
  target=lambda: (
    time.sleep(10),
    os.kill(pid, signal.SIGUSR1)))
thread.start()

因此，这个程序：

import signal
import os
import time

def receive_signal(signum, stack):
    print 'Received:', signum

signal.signal(signal.SIGUSR1, receive_signal)
signal.signal(signal.SIGUSR2, receive_signal)
signal.signal(signal.SIGALRM, receive_signal)  # <-- THIS LINE ADDED

print 'My PID is:', os.getpid()

signal.alarm(10)                               # <-- THIS LINE ADDED

while True:
    print 'Waiting...'
    time.sleep(3)

产生这个输出：

$ python /tmp/x.py 
My PID is: 3029
Waiting...
Waiting...
Waiting...
Waiting...
Received: 14
Waiting...
Waiting...