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python - How to use thread in asyncio?

问题描述

I want to new a thread to do a io task with consumer/producer pattern in a asyncio task:

import asyncio
import threading
import time
import queue


q = queue.Queue()


def consumer():
    while True:
        v = q.get()
        time.sleep(v)
        print(f"log {v}")


async def work(v):
    await asyncio.sleep(0.1)
    print(f"work {v}")


async def main():
    t = threading.Thread(target=consumer, daemon=True)
    t.start()
    for i in range(1, 5):
        print(f"start {i}")
        q.put(i)
        loop.create_task(work(i))
        print(f"done {i}")
    t.join()


loop = asyncio.get_event_loop()
loop.run_until_complete(main())
loop.run_forever()

But the asyncio task cannot be execute because of consumer thread.

标签： pythonmultithreadingpython-asyncio

解决方案

您可以使用内置在 asyncio 中的线程池（或根据需要创建自己的线程池）并调用run_in_executor以向其提交任务，而不是显式管理工作线程和队列。例如：

import asyncio, time

def blocking_work(v):
    # this function is not async, it will be run in a separate thread
    time.sleep(v)
    print(f"log {v}")

async def work(v):
    # native asyncio work
    await asyncio.sleep(0.1)
    # followed by blocking IO wrapped in thread
    loop = asyncio.get_event_loop()
    await loop.run_in_executor(None, blocking_work, v)
    print(f"work {v}")

async def main():
    await asyncio.gather(*[work(i) for i in range(1, 5)])

asyncio.run(main())

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