python - Python asyncio 是否使用线程池？

Question

我写了这段代码:

import asyncio
import threading
from aiohttp import ClientSession

async def fetch(url):
    async with ClientSession() as session:
        async with session.get(url) as response:
            response = await response.read()
            print(threading.current_thread().name)


loop = asyncio.get_event_loop()

tasks = [asyncio.ensure_future(fetch("http://example.com")) for i in range(5)]

loop.run_until_complete(asyncio.wait(tasks))

它每次都打印出“MainThread”。这是否意味着所有请求都使用同一个主线程并发执行，而不是使用线程池中的线程来执行每个请求，或者线程是否被抽象化？

这篇文章似乎表明实际上有一个 Python 用于这些异步任务的线程池: http://skipperkongen.dk/2016/09/09/easy-parallel-http-requests-with-python-and-asyncio/

Answer 1

It prints out "MainThread" every time. Does this mean that all of the requests are being executed concurrently using the same main thread and it's not using threads from a thread pool to execute each request or are the threads being abstracted?

它不使用工作线程，asyncio 只会使用主线程。并发是通过使用 Python 生成器的协作式多任务处理实现的(阅读 coroutines )。

This post seems to show that in fact there is a thread pool ...

除了 asyncio 模块，您链接的博文还明确使用了 concurrent.futures 模块。该代码中的 ThreadPoolExecutor 类将产生工作线程。但是您问题中的示例代码不会。