Python 3.12.3中Quart+Hypercorn报错RuntimeError:无运行事件循环

问题场景 #

使用以下命令启动Quart+Hypercorn服务器：

pipenv run hypercorn --config=hypercorn.toml --reload src.main:app

hypercorn.toml配置内容：

accesslog = "/var/log/pythonrestapi"
errorlog = "/var/log/pythonrestapi"
alt_svc_headers = ["h3=\":443\"; ma=3600, h3-29=\":443\"; ma=3600"]
quic_bind = "0.0.0.0:4433"
bind = "0.0.0.0:4433"
insecure_bind = "0.0.0.0:8080"
certfile = "server.crt"
keyfile = "server.key"
#server_names = ["pythonrestapi"]
worker_class = "trio"

启动后触发报错：

2024-05-29 13:31:33 INFO     Running on https://0.0.0.0:4433 (CTRL + C to quit)
2024-05-29 13:31:33 INFO     Running on http://0.0.0.0:8080 (CTRL + C to quit)
2024-05-29 13:31:34 INFO     Running on https://0.0.0.0:4433 (QUIC) (CTRL + C to quit)
2024-05-29 13:33:09 ERROR    Error in ASGI Framework
Traceback (most recent call last):
  File "/home/khteh/.local/share/virtualenvs/PythonRestAPI-6TwrpjXm/lib/python3.12/site-packages/hypercorn/trio/task_group.py", line 26, in _handle
    await app(scope, receive, send, sync_spawn, call_soon)
  File "/home/khteh/.local/share/virtualenvs/PythonRestAPI-6TwrpjXm/lib/python3.12/site-packages/hypercorn/app_wrappers.py", line 34, in __call__
    await self.app(scope, receive, send)
  File "/home/khteh/.local/share/virtualenvs/PythonRestAPI-6TwrpjXm/lib/python3.12/site-packages/quart/app.py", line 1667, in __call__
    await self.asgi_app(scope, receive, send)
  File "/home/khteh/.local/share/virtualenvs/PythonRestAPI-6TwrpjXm/lib/python3.12/site-packages/quart/app.py", line 1693, in asgi_app
    await asgi_handler(receive, send)
  File "/home/khteh/.local/share/virtualenvs/PythonRestAPI-6TwrpjXm/lib/python3.12/site-packages/quart/asgi.py", line 48, in __call__
    done, pending = await asyncio.wait(
                    ^^^^^^^^^^^^^^^^^^^
  File "/usr/lib/python3.12/asyncio/tasks.py", line 463, in wait
    loop = events.get_running_loop()
           ^^^^^^^^^^^^^^^^^^^^^^^^^
RuntimeError: no running event loop

相关核心代码：
src/main.py：

from src.app import create_app
app = create_app()
app = cors(app, allow_credentials=True, allow_origin="https://localhost:4433")
Healthz(app, no_log=True)
csrf = CSRFProtect(app)
bcrypt.init_app(app)

src/app.py：

def create_app() -> Quart:
    """
    Create App
    """
    # App initialization
    app = Quart(__name__, template_folder='view/templates', static_url_path='', static_folder='view/static')
    app.config.from_file("/etc/pythonrestapi_config.json", json.load)
    if "SQLALCHEMY_DATABASE_URI" not in app.config:
        app.config["SQLALCHEMY_DATABASE_URI"] = f"postgresql://{os.getenv('POSTGRESQL_USER')}:{os.getenv('POSTGRESQL_PASSWORD')}@svc-postgresql/library"
    app.register_blueprint(home_blueprint, url_prefix="/")
    app.register_blueprint(fibonacci_blueprint, url_prefix="/fibonacci")
    app.register_blueprint(auth_blueprint, url_prefix="/auth")
    app.register_blueprint(user_blueprint, url_prefix="/users")
    app.register_blueprint(author_blueprint, url_prefix="/authors")
    app.register_blueprint(book_blueprint, url_prefix="/books")
    db.init_app(app)
    return app

问题原因 #

配置中指定worker_class = "trio"，Hypercorn会使用trio异步框架运行服务，但Quart默认基于asyncio，在trio环境中调用asyncio.wait时，找不到asyncio的事件循环，因此触发RuntimeError。

解决方案 #

方案1：切换到asyncio worker #

修改hypercorn.toml中的worker_class配置，改用默认的asyncio worker：

# 注释或删除原trio配置，或者显式指定asyncio
# worker_class = "trio"
worker_class = "asyncio"

方案2：启用Quart的trio兼容模式 #

如果必须使用trio，需要让Quart适配trio环境：

1. 安装quart-trio依赖：

pipenv install quart-trio

2. 修改src/app.py中Quart的初始化代码，指定async_mode="trio"：

def create_app() -> Quart:
    """
    Create App
    """
    # App initialization - 添加async_mode参数
    app = Quart(
        __name__,
        template_folder='view/templates',
        static_url_path='',
        static_folder='view/static',
        async_mode="trio"  # 新增该行
    )
    app.config.from_file("/etc/pythonrestapi_config.json", json.load)
    if "SQLALCHEMY_DATABASE_URI" not in app.config:
        app.config["SQLALCHEMY_DATABASE_URI"] = f"postgresql://{os.getenv('POSTGRESQL_USER')}:{os.getenv('POSTGRESQL_PASSWORD')}@svc-postgresql/library"
    app.register_blueprint(home_blueprint, url_prefix="/")
    app.register_blueprint(fibonacci_blueprint, url_prefix="/fibonacci")
    app.register_blueprint(auth_blueprint, url_prefix="/auth")
    app.register_blueprint(user_blueprint, url_prefix="/users")
    app.register_blueprint(author_blueprint, url_prefix="/authors")
    app.register_blueprint(book_blueprint, url_prefix="/books")
    db.init_app(app)
    return app

内容的提问来源于stack exchange，提问作者khteh