Multiprocessing RuntimeError and EOFError in Python Keyboard Input Code

[ugoi]

Issue: RuntimeError with multiprocessing in lol.py script

Description

When running the lol.py script, an error occurs related to multiprocessing. It suggests that a process has started incorrectly before finishing its bootstrapping phase, and the usage of if __name__ == '__main__' is recommended. The issue arises from the inputs library's call to multiprocessing. Additionally, there is an AttributeError and an EOFError.

Steps to Reproduce

1. Run lol.py with the following script:

   from inputs import get_key
   while 1:
       print("Start")
       events = get_key()
       for event in events:
           print(event.ev_type, event.code, event.state)

2. Observe the console output for error messages.

Error Output

python3 lol.py
Start
Start
Traceback (most recent call last):
  File "<string>", line 1, in <module>
    from multiprocessing.spawn import spawn_main; spawn_main(tracker_fd=6, pipe_handle=8)
  File ".../multiprocessing/spawn.py", line 122, in spawn_main
    exitcode = _main(fd, parent_sentinel)
  File ".../multiprocessing/spawn.py", line 131, in _main
    prepare(preparation_data)
  File ".../multiprocessing/spawn.py", line 246, in prepare
    _fixup_main_from_path(data['init_main_from_path'])
  File ".../multiprocessing/spawn.py", line 297, in _fixup_main_from_path
    main_content = runpy.run_path(main_path, run_name="__mp_main__")
  File ".../inputs.py", line 3661, in get_key
    return keyboard.read()
  File ".../inputs.py", line 2517, in read
    return next(iter(self))
  File ".../inputs.py", line 2471, in __iter__
    event = self._do_iter()
  File ".../inputs.py", line 2495, in _do_iter
    data = self._get_data(read_size)
  File ".../inputs.py", line 2575, in _get_data
    return self._pipe.recv_bytes()
  File ".../multiprocessing/process.py", line 121, in start
    self._popen = self._Popen(self)
  File ".../multiprocessing/context.py", line 224, in _Popen
    return _default_context.get_context().Process._Popen(process_obj)
  File ".../multiprocessing/context.py", line 289, in _Popen
    return Popen(process_obj)
  File ".../multiprocessing/popen_spawn_posix.py", line 32, in __init__
    super().__init__(process_obj)
  File ".../multiprocessing/popen_fork.py", line 20, in __init__
    self._launch(process_obj)
  File ".../multiprocessing/popen_spawn_posix.py", line 42, in _launch
    prep_data = spawn.get_preparation_data(process_obj._name)
  File ".../multiprocessing/spawn.py", line 164, in get_preparation_data
    _check_not_importing_main()
  File ".../multiprocessing/spawn.py", line 140, in _check_not_importing_main
    raise RuntimeError('''
RuntimeError: 
        An attempt has been made to start a new process before the
        current process has finished its bootstrapping phase.

Exception ignored in: <function InputDevice.__del__ at 0x...>
Traceback (most recent call last):
  File ".../inputs.py", line 2541, in __del__
  File ".../multiprocessing/process.py", line 133, in terminate
AttributeError: 'NoneType' object has no attribute 'terminate'
Traceback (most recent call last):
  File ".../lol.py", line 4, in <module>
    events = get_key()
  File ".../inputs.py", line 3661, in get_key
    return keyboard.read()
  File ".../inputs.py", line 2517, in read
    return next(iter(self))
  File ".../inputs.py", line 2471, in __iter__
    event = self._do_iter()
  File ".../inputs.py", line 2495, in _do_iter
    data = self._get_data(read_size)
  File ".../inputs.py", line 2575, in _get_data
    return self._pipe.recv_bytes()
  File ".../multiprocessing/connection.py", line 216, in recv_bytes
    buf = self._recv_bytes(maxlength)
  File ".../multiprocessing/connection.py", line 430, in _recv_bytes
    buf = self._recv(4)
  File ".../multiprocessing/connection.py", line 399, in _recv
    raise EOFError
EOFError

Environment

• OS: macOS
• Python Version: 3.13.0
• Library: inputs