Python 脚本在没有 shell 的情况下运行时会跳过某些行

Question

我有这样的代码：

from stomp import *
from stomp.listener import ConnectionListener
from stomp.utils import parse_frame

class MyListener(ConnectionListener):
  _counter=0
  def on_message(self, frame):
    if self._counter > 10:
      return
    print(self._counter)
    self._counter += 1

print('Starting...')
connection = Connection([('darwin-dist-44ae45.nationalrail.co.uk', '61613')])
connection.set_listener('', MyListener())
connection.connect(REDACTED)
connection.subscribe('/topic/darwin.pushport-v16', 11)
print('Ummm...???')

当我使用 Python 从命令行运行它时，带有

connection

的行不会执行：

$ python3 myscript.py                                                                                                                                       
Starting...
Ummm...???

但是，当我打开 python shell 并一个一个地运行这些命令时，

connection.subscribe('/topic/darwin.pushport-v16', 11)

会按预期产生一堆输出：

$ python3
>>> from stomp import *
>>> from stomp.listener import ConnectionListener
>>> from stomp.utils import parse_frame
>>> 
>>> class MyListener(ConnectionListener):
...   _counter=0
...   def on_message(self, frame):
...     if self._counter > 10:
...       return
...     print(self._counter)
...     self._counter += 1
... 
>>> print('Starting...')
Starting...
>>> connection = Connection([('darwin-dist-44ae45.nationalrail.co.uk', '61613')])
>>> connection.set_listener('', MyListener())
>>> connection.connect('DARWINba0475e0-225d-49e3-8ba7-ee150d948992', 'c10e58e0-2d2d-4776-b4b8-f7e0e50047de')
>>> connection.subscribe('/topic/darwin.pushport-v16', 11)
0
1
2

我以前从未遇到过这样的奇怪行为。为什么会发生这种情况，我该如何解决？ 谢谢