Python异步程序不会退出等待stdin输入。

Question

我有一个复杂的Python3.9程序，如果被Ctrl (SIGINT)中断，它不会退出。下面是这个问题的最小再现。使用python sample.py运行时，您应该会看到两个输入提示，然后是一个正常的退出。如果在第一个提示符上按下Ctrl，它就会像预期的那样退出。如果在第二个提示符下按下Ctrl，什么都不会发生，直到您按下Enter (然后在selectors.py的深处发生一个不知名的selectors.py)。

import asyncio

async def ainput(prompt: str = "") -> str:
    return await asyncio.get_event_loop().run_in_executor(None, input, prompt)

async def main():
    try:
        input("1>")             # ctrl-C here works as expected, prints the message and exits
        await ainput("2>")      # ctrl-C here does nothing until you hit Enter
    except KeyboardInterrupt:
        print("Ctrl-C")

asyncio.run(main())

问题

这是上面代码中的错误吗？还是异步中的一个bug？我怎么才能解决这个问题？

输出

$ python sample.py
1>asks
2>lsls
$ python sample.py
1>^CCtrl-C
$ python sample.py
1>slsl
2>^C # **nothing happens here until you hit Enter**
Traceback (most recent call last):
  File "/Users/me/work/experimental/sample.py", line 15, in <module>
    asyncio.run(main())
  File "/opt/homebrew/Caskroom/miniforge/base/envs/alexa/lib/python3.9/asyncio/runners.py", line 44, in run
    return loop.run_until_complete(main)
  File "/opt/homebrew/Caskroom/miniforge/base/envs/alexa/lib/python3.9/asyncio/base_events.py", line 634, in run_until_complete
    self.run_forever()
  File "/opt/homebrew/Caskroom/miniforge/base/envs/alexa/lib/python3.9/asyncio/base_events.py", line 601, in run_forever
    self._run_once()
  File "/opt/homebrew/Caskroom/miniforge/base/envs/alexa/lib/python3.9/asyncio/base_events.py", line 1869, in _run_once
    event_list = self._selector.select(timeout)
  File "/opt/homebrew/Caskroom/miniforge/base/envs/alexa/lib/python3.9/selectors.py", line 562, in select
    kev_list = self._selector.control(None, max_ev, timeout)
KeyboardInterrupt

Answer 1

所发生的是KeyboardInterrupt被asyncio捕获，因为您正在使用threading。然后，asyncio通过尝试取消它来将其输入协同线，这会引发asyncio.CancelledError。你可以这样处理：

async def main():
    try:
        input("1>")
        await ainput("2>")
    except KeyboardInterrupt:
        print("Ctrl-C")
    except asyncio.CancelledError:
        print("Cancelled?")
        raise

但是，没有任何方法阻止asyncio.run(...)提高KeyboardInterrupt，至少AFAIK是这样的。