python runtime_error ai_generated true

RuntimeError: Event loop is closed

ID: python/pytest-asyncio-event-loop-closed

Also available as: JSON · Markdown · 中文
80%Fix Rate
85%Confidence
0Evidence
2024-05-10First Seen

Version Compatibility

VersionStatusIntroducedDeprecatedNotes
0.21 active — — —
0.23 active — — —

Root Cause

pytest-asyncio creates a new event loop per test by default. If an async resource (e.g., aiohttp session, async DB connection) is created in one test and used in another, or if the loop is closed before cleanup, this error occurs.

generic

中文

pytest-asyncio 默认每个测试创建一个新的事件循环。如果异步资源（如 aiohttp 会话、异步数据库连接）在一个测试中创建并在另一个测试中使用，或者在清理前循环已关闭，就会发生此错误。

Workarounds

  1. 95% success 
    In conftest.py:
import pytest
import asyncio

@pytest.fixture(scope='session')
def event_loop():
    loop = asyncio.new_event_loop()
    yield loop
    loop.close()

Or use pytest-asyncio's built-in: set asyncio_mode = auto and use @pytest.mark.asyncio(scope='session').
  2. 90% success 
    @pytest_asyncio.fixture(scope='module')
async def client():
    session = aiohttp.ClientSession()
    yield session
    await session.close()

Dead Ends

Common approaches that don't work:

  1. 90% fail

    Sleeping does not prevent the loop from being closed between tests.

  2. 85% fail

    This only affects Windows and does not address the per-test loop creation.