python 限制函数执行时间,自己实现timeout的实例

# coding=utf-8import signalimport time  def set_timeout(num, callback):  def wrap(func):    def handle(signum, frame): # 收到信号 SIGALRM 后的回调函数，第一个参数是信号的数字，第二个参数是the interrupted stack frame.      raise RuntimeError     def to_do(*args, **kwargs):      try:        signal.signal(signal.SIGALRM, handle) # 设置信号和回调函数        signal.alarm(num) # 设置 num 秒的闹钟        print 'start alarm signal.'        r = func(*args, **kwargs)        print 'close alarm signal.'        signal.alarm(0) # 关闭闹钟        return r      except RuntimeError as e:        callback()     return to_do   return wrap  if __name__ == '__main__':  def after_timeout(): # 超时后的处理函数    print "do something after timeout."    @set_timeout(2, after_timeout) # 限时 2 秒  def connect(): # 要执行的函数    time.sleep(1) # 函数执行时间，写大于2的值，可测试超时    return 'connect success.'    print connect()