PyCharm调试模式下WindowsSelectorEventLoopPolicy引发Task不可调用异常

问题场景 #

• 代码在普通运行模式、或使用默认Proactor事件循环的调试模式下均可正常执行
• 默认Proactor策略会导致应用中loop.add_reader()/loop.add_writer()抛出NotImplementedError，无法使用
• 切换为WindowsSelectorEventLoopPolicy后，普通运行正常，但调试模式下触发TypeError: 'Task' object is not callable异常

简化示例代码 #

import asyncio
import os
import sys

if sys.version_info >= (3, 8) and os.name == "nt":
    # 用于支持loop.add_reader等方法
    asyncio.set_event_loop_policy(asyncio.WindowsSelectorEventLoopPolicy())
    # 该策略可解决当前调试报错，但会导致add_reader/add_writer失效
    # asyncio.set_event_loop_policy(asyncio.WindowsProactorEventLoopPolicy())

async def main() -> None:
    print("foo")

if __name__ == '__main__':
    try:
        asyncio.run(main())
    except KeyboardInterrupt:
        pass

运行结果 #

• 普通运行模式：

foo

• 调试模式报错信息：

Exception in callback <Task pending name='Task-1'
    coro=<main() running at C:\...\a.py:21>
    cb=[_run_until_complete_cb() at C:\... Python.3.11_3.11.2544.0_x64__qbz5n2kfra8p0\Lib\asyncio\base_events.py:181]>())
handle: <Handle <Task pending name='Task-1'
    coro=<main() running at C:\...\a.py:21>
    cb=[_run_until_complete_cb() at C:\... Python.3.11_3.11.2544.0_x64__qbz5n2kfra8p0\Lib\asyncio\base_events.py:181]>())>
Traceback (most recent call last):
  File "C:\... Python.3.11_3.11.2544.0_x64__qbz5n2kfra8p0\Lib\asyncio\events.py", line 84, in _run
    self._context.run(self._callback, *self._args)
TypeError: 'Task' object is not callable

环境信息 #

• Windows应用商店Python 3.11
• PyCharm 2025.1.2（Build #PY-251.26094.141）

解决方案 #

1. 显式创建事件循环替代asyncio.run() #

修改代码，手动创建并管理事件循环，避免调试器钩子与asyncio.run()的冲突：

import asyncio
import os
import sys

if sys.version_info >= (3, 8) and os.name == "nt":
    asyncio.set_event_loop_policy(asyncio.WindowsSelectorEventLoopPolicy())

async def main() -> None:
    print("foo")

if __name__ == '__main__':
    try:
        loop = asyncio.new_event_loop()
        asyncio.set_event_loop(loop)
        loop.run_until_complete(main())
    except KeyboardInterrupt:
        pass
    finally:
        loop.close()

2. 调整PyCharm调试器配置 #

• 打开Run/Debug Configurations
• 选择当前调试配置，切换到Configuration标签页
• 勾选Emulate terminal in output console选项
• 保存后重新启动调试

3. 版本适配 #

• 可尝试降级Python至3.10或更早版本，该兼容性问题在旧版本中可能不存在
• 关注PyCharm官方更新，等待JetBrains修复该调试器与Selector事件循环的兼容bug

内容的提问来源于stack exchange，提问作者nipil