How to terminate a Python3 thread correctly while it's reading a stream
I'm using a thread to read Strings from a stream (/dev/tty1) while processing other things in the main loop. I would like the Thread to terminate together with the main program when pressing CTRL-C.
from threading import Thread
class myReader(Thread):
def run(self):
with open('/dev/tty1', encoding='ascii') as myStream:
for myString in myStream:
print(myString)
def quit(self):
pass # stop reading, close stream, terminate the thread
myReader = Reader()
myReader.start()
开发者_JAVA技巧 while(True):
try:
pass # do lots of stuff
KeyboardInterrupt:
myReader.quit()
raise
The usual solution - a boolean variable inside the run() loop - doesn't work here. What's the recommended way to deal with this?
I can just set the Daemon flag, but then I won't be able to use a quit() method which might prove valuable later (to do some clean-up). Any ideas?
AFAIK, there is no built-in mechanism for that in Python 3 (just as in Python 2). Have you tried the proven Python 2 approach with PyThreadState_SetAsyncExc
, documented here and here, or the alternative tracing approach here?
Here's a slightly modified version of the PyThreadState_SetAsyncExc
approach from above:
import threading
import inspect
import ctypes
def _async_raise(tid, exctype):
"""raises the exception, performs cleanup if needed"""
if not inspect.isclass(exctype):
exctype = type(exctype)
res = ctypes.pythonapi.PyThreadState_SetAsyncExc(ctypes.c_long(tid), ctypes.py_object(exctype))
if res == 0:
raise ValueError("invalid thread id")
elif res != 1:
# """if it returns a number greater than one, you're in trouble,
# and you should call it again with exc=NULL to revert the effect"""
ctypes.pythonapi.PyThreadState_SetAsyncExc(tid, None)
raise SystemError("PyThreadState_SetAsyncExc failed")
def stop_thread(thread):
_async_raise(thread.ident, SystemExit)
Make your thread a daemon thread. When all non-daemon threads have exited, the program exits. So when Ctrl-C is passed to your program and the main thread exits, there's no need to explicitly kill the reader.
myReader = Reader()
myReader.daemon = True
myReader.start()
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