Hi all,
recently I’ve been playing around with sending and catching signals on
Windows. I finally found out how to send and catch a BREAK event.
With Python 2.7(.2), I only need os.kill(pid, signal.CTRL_C_EVENT) and
signal.signal(signal.SIGBREAK, handler). Alternatively, I can use
GenerateConsoleCtrlEvent and SetConsoleCtrlHandler via ctypes.
However, the former does not work with Python 3.3 (64bit) and the latter
always raises a KeyError in Python’s threading module.
My question is: Should signal.signal(signal.SIGBREAK, handler) work
under Python 3.3? If so, what am I doing wrong? Why raises the
ctypes-variant an error while the signal-variant doesn’t?
Below is a minimal example illustrating my problem:
# sigterm_min.py
import os
import signal
import subprocess
import sys
import time
WIN = (sys.platform == 'win32')
kwargs = {}
if WIN:
kwargs['creationflags'] = subprocess.CREATE_NEW_PROCESS_GROUP
def parent():
proc = subprocess.Popen(['python', 'sigterm_min.py', 'child'],
**kwargs)
time.sleep(1)
if WIN:
# This works on Python 2.7 and 3.3:
os.kill(proc.pid, signal.CTRL_BREAK_EVENT)
# Alternative (ugly) way:
# import ctypes
# ctypes.windll.kernel32.GenerateConsoleCtrlEvent(
# signal.CTRL_BREAK_EVENT, proc.pid)
else:
proc.terminate()
print('parent waiting for child')
proc.wait()
print('parent terminating')
def child():
def handler(signum, frame=None):
print('child terminating')
sys.exit(0)
if WIN:
# This only works on Python 2.7, but not on 3.3:
signal.signal(signal.SIGBREAK, handler)
# (Ugly) alternative that works on both Python 2.7 and 3.3,
# but raises a KeyError in threading.py:
# import ctypes
# handler = ctypes.WINFUNCTYPE(ctypes.c_int,
# ctypes.c_uint)(handler)
# ctypes.windll.kernel32.SetConsoleCtrlHandler(handler, True)
else:
signal.signal(signal.SIGTERM, handler)
time.sleep(10)
if __name__ == '__main__':
if len(sys.argv) == 1:
parent()
elif sys.argv[1] == 'child':
child()
# EOF
Cheers,
Stefan
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