同一代码运行FastAPI与Telegram Bot报错，求解决方法

我用FastAPI开发了一个处理Webhook的Python应用，尝试集成Telegram Bot，但使用threading启动Telegram服务时无法正常工作，出现以下错误：

Uvicorn running on http://0.0.0.0:8383 (Press CTRL+C to quit)
Bot is running...
Exception in thread Thread-2 (run_telegram_bot):
Traceback (most recent call last):
  File "/Library/Frameworks/Python.framework/Versions/3.10/lib/python3.10/threading.py", line 1016, in _bootstrap_inner
    self.run()
  File "/Library/Frameworks/Python.framework/Versions/3.10/lib/python3.10/threading.py", line 953, in run
    self._target(*self._args, **self._kwargs)
  File "/Users/yosef/uni/Uni chat store/index.py", line 23, in run_telegram_bot
    TelegramNotification().lunch_bot()
  File "/Users/yosef/uni/Uni chat store/utils/telegram/send_notifictions.py", line 51, in lunch_bot
    application.run_polling(1.0)
  File "/Users/yosef/.local/share/virtualenvs/Uni_chat_store-eDiP6l1M/lib/python3.10/site-packages/telegram/ext/_application.py", line 836, in run_polling
    return self.__run(
  File "/Users/yosef/.local/share/virtualenvs/Uni_chat_store-eDiP6l1M/lib/python3.10/site-packages/telegram/ext/_application.py", line 1007, in __run
    loop = asyncio.get_event_loop()
  File "/Library/Frameworks/Python.framework/Versions/3.10/lib/python3.10/asyncio/events.py", line 656, in get_event_loop
    raise RuntimeError('There is no current event loop in thread %r.'
RuntimeError: There is no current event loop in thread 'Thread-2 (run_telegram_bot)'.
/Library/Frameworks/Python.framework/Versions/3.10/lib/python3.10/threading.py:1018: RuntimeWarning: coroutine 'Updater.start_polling' was never awaited
  self._invoke_excepthook(self)
RuntimeWarning: Enable tracemalloc to get the object allocation traceback

相关代码 #

TelegramNotification类的启动函数

def lunch_bot(self):
        application = Application.builder().token(self.BOT_TOKEN).build()
        print('Bot is running...')

        # Commands
        application.add_handler(CommandHandler('start', self.start))

        # Run bot
        application.run_polling(1.0)

index.py文件内容

from fastapi import FastAPI
from routers import whatsapp_webhook, payment_method_form
from fastapi.middleware.cors import CORSMiddleware
import uvicorn
from utils.telegram.send_notifictions import TelegramNotification
import threading

app = FastAPI()

app.add_middleware(
    CORSMiddleware,
    allow_origins=["*"],  # Allows all origins
    allow_credentials=True,
    allow_methods=["*"],  # Allows all methods
    allow_headers=["*"],  # Allows all headers
)

app.include_router(whatsapp_webhook.router)
app.include_router(payment_method_form.router)


def run_telegram_bot():
    TelegramNotification().lunch_bot()

# run the whatsapp webhook 
def run_whatsapp_webhook():
    uvicorn.run("index:app", host="0.0.0.0", port=8383)


if __name__ == '__main__':

    threading.Thread(target=run_whatsapp_webhook).start()
    threading.Thread(target=run_telegram_bot).start()

解决方案 #

报错原因是子线程默认没有创建asyncio事件循环，而python-telegram-bot v20+版本的run_polling依赖异步事件循环。只需修改run_telegram_bot函数，在子线程中手动创建并设置事件循环即可：

def run_telegram_bot():
    import asyncio
    # 为子线程创建并设置asyncio事件循环
    loop = asyncio.new_event_loop()
    asyncio.set_event_loop(loop)
    TelegramNotification().lunch_bot()

如果希望更贴合异步编程规范，也可以把lunch_bot改为异步函数，再通过事件循环运行：

修改TelegramNotification类的lunch_bot方法

async def lunch_bot(self):
        application = Application.builder().token(self.BOT_TOKEN).build()
        print('Bot is running...')

        # Commands
        application.add_handler(CommandHandler('start', self.start))

        # Run bot
        await application.run_polling(1.0)

修改run_telegram_bot函数

def run_telegram_bot():
    import asyncio
    loop = asyncio.new_event_loop()
    asyncio.set_event_loop(loop)
    loop.run_until_complete(TelegramNotification().lunch_bot())

这样修改后，Telegram Bot就能在子线程中正常运行，同时不影响FastAPI的Webhook服务。

内容的提问来源于stack exchange，提问作者Yosef Schwartz