线程忽略了KeyboardInterrupt异常

Question

我在运行这段简单的代码：

import threading, time

class reqthread(threading.Thread):    
    def run(self):
        for i in range(0, 10):
            time.sleep(1)
            print('.')

try:
    thread = reqthread()
    thread.start()
except (KeyboardInterrupt, SystemExit):
    print('\n! Received keyboard interrupt, quitting threads.\n')

但是当我运行它的时候，它输出了：

$ python prova.py
.
.
^C.
.
.
.
.
.
.
.
Exception KeyboardInterrupt in <module 'threading' from '/usr/lib/python2.6/threading.pyc'> ignored

实际上，Python 线程忽略了我按的 Ctrl+C 中断键，并没有打印出 Received Keyboard Interrupt。这是为什么呢？这段代码有什么问题吗？

Answer 1

这是对Ubuntu解决方案的一个小修改。

根据Eric的建议，去掉了 tread.daemon = True，并把原来的睡眠循环换成了signal.pause()：

import signal

try:
  thread = reqthread()
  thread.start()
  signal.pause()  # instead of: while True: time.sleep(100)
except (KeyboardInterrupt, SystemExit):
  print('Received keyboard interrupt, quitting threads.)

Answer 2

为了总结在这个和这个评论中推荐的修改，以下内容对我来说效果很好：

try:
  thread = reqthread()
  thread.start()
  while thread.isAlive(): 
    thread.join(1)  # not sure if there is an appreciable cost to this.
except (KeyboardInterrupt, SystemExit):
  print '\n! Received keyboard interrupt, quitting threads.\n'
  sys.exit()

Answer 3

试试这个

try:
    thread = reqthread()
    thread.daemon = True
    thread.start()
    while True:
        time.sleep(100)
except (KeyboardInterrupt, SystemExit):
    print('Received keyboard interrupt, quitting threads.')
 

如果不调用 time.sleep，主程序会太早跳出 try...except 这个块，所以 KeyboardInterrupt 就捕捉不到了。我最开始的想法是用 thread.join，但这样会让主程序一直等着，直到这个 thread 完成，期间会忽略 KeyboardInterrupt。

设置 thread.daemon=True 的话，线程会在主程序结束时自动终止。