我正在尝试在 Windows 上测试一些异步功能。我正在使用 Python 3.7。

这会提示一些 NotImplementedError

import asyncio
import os
import time
import sys

#this works
async def say_after(delay, what):
    await asyncio.sleep(delay)
    print(what)

#this doesn't
async def test_async(num):
    print('Task #{0} start'.format(num))

    proc = await asyncio.create_subprocess_shell(
        'C:/Python37/python test_repl.py',
        stdout=asyncio.subprocess.PIPE,
        stderr=asyncio.subprocess.PIPE,
        stdin=asyncio.subprocess.PIPE )

    stdout, stderr = await proc.communicate("sleep 10")
    cmd = 'python'
    print(f'[{cmd!r} exited with {proc.returncode}]')
    if stdout:
        print(f'[stdout]\n{stdout.decode()}')
    if stderr:
        print(f'[stderr]\n{stderr.decode()}')

async def test_loop():
    task1 = asyncio.create_task(
        test_async(1))

    task2 = asyncio.create_task(
        test_async(2))

    print(f"started at {time.strftime('%X')}")

    await task1
    await task2

    print(f"finished at {time.strftime('%X')}")

loop = asyncio.ProactorEventLoop()
asyncio.set_event_loop(loop)
asyncio.run(test_loop())

我尝试了几种循环类型(Protractor 和 Default)。我已经通过 shell 尝试了不同的功能并直接调用程序(子进程术语中的 _shell 和 _exec)。似乎没有任何效果。对于我读过的关于 asyncio 的大肆宣传，它不可能是 Linux 独有的东西。我一定做错了什么。你能给我指出正确的方向吗？

我得到的具体错误如下:

--------------Async--------------------
started at 22:39:55
Task #1 start
Task #2 start
Traceback (most recent call last):
  File "multirun.py", line 45, in <module>
    asyncio.run(test_loop())
  File "C:\Python37\lib\asyncio\runners.py", line 43, in run
    return loop.run_until_complete(main)
  File "C:\Python37\lib\asyncio\base_events.py", line 568, in run_until_complete
    return future.result()
  File "multirun.py", line 38, in test_loop
    await task1
  File "multirun.py", line 20, in test_async
    stdin=asyncio.subprocess.PIPE)
  File "C:\Python37\lib\asyncio\subprocess.py", line 202, in create_subprocess_shell
    stderr=stderr, **kwds)
  File "C:\Python37\lib\asyncio\base_events.py", line 1486, in subprocess_shell
    protocol, cmd, True, stdin, stdout, stderr, bufsize, **kwargs)
  File "C:\Python37\lib\asyncio\base_events.py", line 444, in _make_subprocess_transport
    raise NotImplementedError
NotImplementedError
Task exception was never retrieved
future: <Task finished coro=<test_async() done, defined at multirun.py:12> exception=NotImplementedError()>
Traceback (most recent call last):
  File "multirun.py", line 20, in test_async
    stdin=asyncio.subprocess.PIPE)
  File "C:\Python37\lib\asyncio\subprocess.py", line 202, in create_subprocess_shell
    stderr=stderr, **kwds)
  File "C:\Python37\lib\asyncio\base_events.py", line 1486, in subprocess_shell
    protocol, cmd, True, stdin, stdout, stderr, bufsize, **kwargs)
  File "C:\Python37\lib\asyncio\base_events.py", line 444, in _make_subprocess_transport
    raise NotImplementedError
NotImplementedError

此外，我在尝试运行记事本时遇到了同样的错误。

最佳答案

从 Python 3.8 开始，这个问题应该不再存在，因为前摄器事件循环现在是 default Windows 上的事件循环。原始答案如下。

问题是，尽管出现，您实际上并没有使用 ProactorEventLoop。 asyncio.run()根据您从未更改过的当前循环创建策略创建一个新的事件循环。为每次运行创建一个新循环通常是一项功能，因为它保证清理与循环相关的资源 - 但在这种情况下它与 example 不兼容。从文档中。 (编辑:此示例已成为 removed，因为 ProactorEventLoop 已成为默认设置。)

快速修复是将 asyncio.run(test_loop()) 更改为 loop.run_until_complete(test_loop())。更好的解决方法是 set the event loop policy到创建前导循环的那个。

关于python - Windows 上的 asyncio create_subprocess_shell python 3.7，我们在Stack Overflow上找到一个类似的问题： https://stackoverflow.com/questions/53127248/