我想ayncio
和使用coroutine
不与线程相关的,因为coroutine
是一种“线”下程序的调度运行的,所以应该只有1个线程运行每个过程。但是,当我在Making 1 million requests with python-aiohttp跑的例子,代码如下图所示:为什么ASYNCIO使与aiohttp请求仍然使用线程的
# modified fetch function with semaphore
import random
import asyncio
from aiohttp import ClientSession
async def fetch(url, session):
async with session.get(url) as response:
delay = response.headers.get("DELAY")
date = response.headers.get("DATE")
print("{}:{} with delay {}".format(date, response.url, delay))
return await response.read()
async def bound_fetch(sem, url, session):
# Getter function with semaphore.
async with sem:
await fetch(url, session)
async def run(r):
url = "http://localhost:8080/{}"
tasks = []
# create instance of Semaphore
sem = asyncio.Semaphore(1000)
# Create client session that will ensure we dont open new connection
# per each request.
async with ClientSession() as session:
for i in range(r):
# pass Semaphore and session to every GET request
task = asyncio.ensure_future(bound_fetch(sem, url.format(i), session))
tasks.append(task)
responses = asyncio.gather(*tasks)
await responses
number = 10000
loop = asyncio.get_event_loop()
future = asyncio.ensure_future(run(number))
loop.run_until_complete(future)
使用Windows'资源监视器,我发现代码1个过程中创建25个线程。