线程中的服务器（Python3.9.0+aiohttp）：RuntimeError：关闭后无法注册atexit

这段代码（在线程中运行的最小服务器，代码取自here https://stackoverflow.com/questions/51610074/how-to-run-an-aiohttp-server-in-a-thread）在 Python3.8.3 上工作正常，但在 Python3.9.0 上会引发错误消息：

import asyncio
import threading
from aiohttp import web


def aiohttp_server():
    def say_hello(request):
        return web.Response(text='Hello, world')

    app = web.Application()
    app.add_routes([web.get('/', say_hello)])
    runner = web.AppRunner(app)
    return runner


def run_server(runner):
    loop = asyncio.new_event_loop()
    asyncio.set_event_loop(loop)
    loop.run_until_complete(runner.setup())
    site = web.TCPSite(runner, 'localhost', 8080)
    loop.run_until_complete(site.start())
    loop.run_forever()


t = threading.Thread(target=run_server, args=(aiohttp_server(),))
t.start()

错误信息：

Exception in thread Thread-1:
Traceback (most recent call last):
  File "/usr/lib/python3.9/threading.py", line 954, in _bootstrap_inner
    self.run()
  File "/usr/lib/python3.9/threading.py", line 892, in run
    self._target(*self._args, **self._kwargs)
  File "/home/alkhinoos/nikw/nikw/z2.py", line 21, in run_server
    loop.run_until_complete(site.start())
  File "/usr/lib/python3.9/asyncio/base_events.py", line 642, in run_until_complete
    return future.result()
  File "/usr/lib/python3.9/site-packages/aiohttp/web_runner.py", line 121, in start
    self._server = await loop.create_server(
  File "/usr/lib/python3.9/asyncio/base_events.py", line 1460, in create_server
    infos = await tasks.gather(*fs, loop=self)
  File "/usr/lib/python3.9/asyncio/base_events.py", line 1400, in _create_server_getaddrinfo
    infos = await self._ensure_resolved((host, port), family=family,
  File "/usr/lib/python3.9/asyncio/base_events.py", line 1396, in _ensure_resolved
    return await loop.getaddrinfo(host, port, family=family, type=type,
  File "/usr/lib/python3.9/asyncio/base_events.py", line 856, in getaddrinfo
    return await self.run_in_executor(
  File "/usr/lib/python3.9/asyncio/base_events.py", line 809, in run_in_executor
    executor = concurrent.futures.ThreadPoolExecutor(
  File "/usr/lib/python3.9/concurrent/futures/__init__.py", line 49, in __getattr__
    from .thread import ThreadPoolExecutor as te
  File "/usr/lib/python3.9/concurrent/futures/thread.py", line 37, in <module>
    threading._register_atexit(_python_exit)
  File "/usr/lib/python3.9/threading.py", line 1374, in _register_atexit
    raise RuntimeError("can't register atexit after shutdown")
RuntimeError: can't register atexit after shutdown

这是怎么回事 ？ Python 3.9.1 也出现同样的问题。 Python 3.9.2 解决了这个问题吗？或许这里有一个相关问题 https://bugs.python.org/issue42647.

正如 Python 手册中提到的 -线程对象 https://docs.python.org/3/library/threading.html#thread-objects

其他线程可以调用一个线程的 join() 方法。这会阻塞调用线程，直到调用 join() 方法的线程终止。

打电话后t.start()在主线程中，主线程将退出。然后该过程结束。

如果你想永远运行子线程或者直到它退出，你应该调用t.join()在主线程之后t.start().