python | 异步、多线程相互纠缠

暂不涉及多进程。

在很多场景，协程是和多线程相互纠缠的

• 协程中运行多线程
  • python | await | 同步 && 异步？
  • 在上面的章节中，我们了解到如果协程中执行非异步代码，会进行阻塞
  • 但是，我们有时候想执行非异步代码的时候，也不阻塞
• 多线程中的协程
  • 这种场景非常有用
  • 我用于数据获取的实时性

协程中运行多线程

import asyncio
import time


async def run0():
    loop = asyncio.get_event_loop()
    loop.run_in_executor(None, time.sleep, 1)
    print("run0")


async def run1():
    loop = asyncio.get_event_loop()
    loop.run_in_executor(None, time.sleep, 2)
    print("run1")


if __name__ == '__main__':
    now = time.time()
    tasks = [
        run0(),
        run1()
    ]
    loop = asyncio.get_event_loop()
    loop.run_until_complete(asyncio.wait(tasks))
    print(time.time() - now)

输出

run1
run0
0.002712249755859375

但是，很明显不对，所以要改成下面这个样子。

import asyncio
import time


async def run0():
    loop = asyncio.get_event_loop()
    f = loop.run_in_executor(None, time.sleep, 1)
    await f
    print("run0")


async def run1():
    loop = asyncio.get_event_loop()
    f = loop.run_in_executor(None, time.sleep, 2)
    await f
    print("run1")


if __name__ == '__main__':
    now = time.time()
    tasks = [
        run0(),
        run1()
    ]
    loop = asyncio.get_event_loop()
    loop.run_until_complete(asyncio.wait(tasks))
    print(time.time() - now)

输出

run0
run1
2.009390115737915

多线程运行协程

import asyncio
from concurrent.futures import ThreadPoolExecutor, as_completed
import time

pools = ThreadPoolExecutor(2)


async def run0():
    await asyncio.sleep(2)
    print("success")


def thread_start():
    asyncio.run(asyncio.wait([run0()]))


now = time.time()
for i in range(0, 2):
    pools.submit(thread_start)
print(time.time() - now)

输出

0.0021479129791259766
success
success