Discord.py 避免阻塞 on_message 方法

Question

我正在开发一个主要处理图像的 Discord 机器人。到目前为止它正在工作，但是当一次发送多个图像时，我遇到了很多阻塞和不一致。

是这样的：

用户上传图片 > 机器人在消息上放置“眼睛”表情符号 > 机器人处理图像 > 机器人响应结果。

但是，有时它可以一次处理多张图像（机器人将眼睛表情符号放在前几张图像上），但通常它只是将表情符号放在第一张图像上，然后在完成那张图像后，它会处理接下来的 2-3图片等

花费大部分时间的过程是OCR读取图像。

这是一些抽象代码：

main.py

@client.event
async def on_message(message):
  ...
  if len(message.attachments) > 0: await message_service.handle_image(message)
  ...

message_service.py

  async def handle_image(self, message):
    supported_attachments = filter_out_unsupported(message.attachments)
    images = []
    await message.reply(f"{random_greeting()} {message.author.mention}, I'm processing your upload(s) please wait a moment, this could take up to 30 seconds.")
    await message.add_reaction('????')
    for a in supported_attachments:
      async with aiohttp.ClientSession() as session:
        async with session.get(a) as res:
          if res.status == 200:
            buffer = io.BytesIO(await res.read())
            arr = np.asarray(bytearray(buffer.read()), dtype=np.uint8)
            images.append(cv2.imdecode(arr, -1))

          for image in images:
            result = await self.image_handler.handle_image(image, message.author)
            await message.remove_reaction('????', message.author)
            if result == None:
              await message.reply(f"{message.author.mention} I can't process your image. It's incorrect, unclear or I'm just not smart enough... :(")
              await message.add_reaction('❌')
            else:
              await message.reply(result)

image_handler

async def handle_image(self, image, author):
    try:
      if image is None: return None

      governor_id = str(self.__get_governor_id_by_discord_id(author.id))
      if governor_id == None:
        return f"{author.mention} there was no account registered under your discord id, please register by using this format: `$register <governor_id> <in game name>`, for example: `$register ... ...`. After that repost the screenshot.\n As for now multiple accounts are not supported."
      
      # This part is most likely the bottleneck !!
      read_result = self.reader.read_image_task(image)
      if self.__no_values_are_found(...):
        return None

      return self.sheets_client.update_player_row_in_sheets(...)
    except:
      return None
    
  def __no_values_are_found(self, *args):
    return all(v is None for v in [*args])


  def __get_governor_id_by_discord_id(self, id):
    return self.sheets_client.get_governor_id_by_discord_id(id)

总的来说，我是 Python 和 Discord 机器人的新手，但有没有一种干净的方法来处理这个问题？

我一直在考虑线程，但在这种情况下似乎找不到很多解决方案，这让我相信我错过了什么或做某事效率低下。

Answer 1

其实有一个干净的方法，你可以创建自己的to_thread装饰器并装饰你的阻塞函数（虽然它们不能是协程，但它们必须是普通的同步函数）

import asyncio
from functools import partial, wraps

def to_thread(func):
    @wraps(func)
    async def wrapper(*args, **kwargs):
        loop = asyncio.get_event_loop()
        callback = partial(func, *args, **kwargs)
        return await loop.run_in_executor(None, callback)  # if using python 3.9+ use `await asyncio.to_thread(callback)`
    return wrapper


# usage
@to_thread
def handle_image(self, image, author):  # notice how it's *not* an async function
    ...


# calling
await handle_image(...)  # not a coroutine, yet I'm awaiting it (cause of the wrapper function)