关闭异步循环答案

【问题标题】：Close asyncio loop关闭异步循环
【发布时间】：2021-07-27 08:41:09
【问题描述】：

import asyncio
import aiohttp
aut_token = ("token")
tasks = []
iter_flag = True
interval = 0
seq = 0
class WAPI:

    async def receiver(WAPI_S):
        async for msg in WAPI_S:
            global interval
            global seq
            data = msg.json()
            seq = data.get("s")
            if data.get("op") == 10:
                interval = data.get("d").get("heartbeat_interval") / 1000 
            if data.get("op") == 11:
                pass
            raise aiohttp.ClientError

    async def heartbeating(WAPI_S):
        while iter_flag:
            await WAPI_S.send_json({
                            "op": 1,
                            "d": seq
                        })
            
            await asyncio.sleep(interval)

    async def event_manager():
        loop = asyncio.get_running_loop()
        try:
            async with aiohttp.ClientSession() as session:
                async with session.ws_connect("url") as WAPI_S: 
                    task_receive = loop.create_task(WAPI.receiver(WAPI_S)); task_heartbeating = loop.create_task(WAPI.heartbeating(WAPI_S))
                    tasks.append(task_receive); tasks.append(task_heartbeating)
                    await asyncio.gather(*tasks)
        except aiohttp.ClientError:
            global iter_flag
            iter_flag = False
            await asyncio.sleep(interval)
            for task in tasks:
                task.cancel()
            try:
                loop.close()
            except:
                loop.stop()
                
asyncio.run(WAPI.event_manager())

我正在尝试通过关闭循环来捕获 ClientError 异常，但是，loop.close 会抛出“RuntimeError：事件循环在 Future 完成之前停止。”

如何正确实现拦截？

【问题讨论】：

标签： python api asynchronous python-asyncio aiohttp

【解决方案1】：

您不需要手动跟踪您的任务，您可以简单地使用

asyncio.all_tasks():

Return a set of not yet finished Task objects run by the loop.

然后是：

pending = asyncio.all_tasks()
c in pending:
    wait_for(c, timeout=5)

此外，您正在尝试停止循环。这是我最常使用的模式：

async def main():
   <do some stuff>

loop = asyncio.get_event_loop()
try:
    loop.run_until_complete(main())
except ExceptionYouWantToHandle:
    <cleaning up>
finally:
    loop.stop()

在 event_manager 中，您只需在获得执行或传递异常后返回

【讨论】：