在单独的线程中执行run_coroutine_threadsafe

Question

我有一个永远运行的脚本（它检查文件中的更改）。每当制作一个奇怪的文件时，我需要发送不和谐的消息

• 问题是，事件监视函数（def run(self):）来自子类，所以我不能将其更改为async def run(self):。因此，我不能使用await channel.send()
• 我的解决方案是使用run_coroutine_threadsafe，就像这里解释的：https://stackoverflow.com/a/53726266/9283107。那很好！但问题是，消息被放入一个队列中，在这个脚本完成之前它们永远不会被发送（在我的例子中是：从不）。我假设发送消息函数被放入这个脚本所在的线程中，因此线程永远无法访问它们

也许我们可以把run_coroutine_threadsafe放进一个单独的线程或者别的什么？这是我能做的最简单的例子，它仍然显示了我的子类问题

import discord
import os
import asyncio
import time

# CHANNEL_ID = 7659170174????????
client = discord.Client()
channel = None

class Example():
    # Imagine this run comes from a subclass, so you can't add sync to it!
    def run(self):
        # await channel.send('Test') # We can't do this because of the above comment
        asyncio.run_coroutine_threadsafe(channel.send('Test'), _loop)
        print('Message sent')

@client.event
async def on_ready():
    print('Discord ready')
    global channel
    channel = client.get_channel(CHANNEL_ID)

    for i in range(2):
        Example().run()
        time.sleep(3)

    print('Discord messages should appear by now. Sleeping for 20s to give it time (technically this would be infinite)')
    time.sleep(20)
    print('Script done. Now they only get sent for some reason')

_loop = asyncio.get_event_loop()

client.run('Your secret token')

Answer 1

在对这个问题发表了user4815162342评论之后，我想到了这个，它非常有效

import discord
import os
import asyncio
import time
import threading

CHANNEL_ID = 7659170174????????
client = discord.Client()
channel = None

class Example():
    # Imagine this run comes from a subclass, so you can't add sync to it!
    def run(self):
        # await channel.send('Test') # We can't do this because of the above comment
        asyncio.run_coroutine_threadsafe(channel.send('Tester'), _loop)
        print('Message sent')

def start_code():
    for i in range(2):
        Example().run()
        time.sleep(20)

@client.event
async def on_ready():
    print('Discord ready')
    global channel
    channel = client.get_channel(CHANNEL_ID)

    threading.Thread(target=start_code).start()

_loop = asyncio.get_event_loop()

client.run('Your secret token')

Answer 2

首先，请注意，不允许从async def调用诸如time.sleep()之类的阻塞代码。要启动阻塞函数并使其与asyncio通信，可以从on_ready甚至从顶层生成一个后台线程，如下所示：

# checker_function is the function that blocks and that
# will invoke Example.run() in a loop.
threading.Thread(
    target=checker_function,
    args=(asyncio.get_event_loop(), channel)
).start()

主线程将运行asyncio事件循环，后台线程将检查文件，使用asyncio.run_coroutine_threadsafe()与asyncio和discord通信

正如您链接到的答案下面的注释所指出的，asyncio.run_coroutine_threadsafe假设您有多个线程正在运行（因此是“线程安全的”），其中一个线程运行事件循环。在实现该功能之前，任何使用asyncio.run_coroutine_threadsafe的尝试都将失败