协程进程的异步打印状态

Question

我有一堆协程在做一些工作

@asyncio.coroutine
def do_work():
    global COUNTER
    result = ...
    if result.status == 'OK':
        COUNTER += 1

和另一个

COUNTER = 0
@asyncio.coroutine
def display_status():
    while True:
        print(COUNTER)
        yield from asyncio.sleep(1)

其中必须显示有多少协程完成了它们的工作。如何正确执行此任务？以下解决方案不起作用

@asyncio.coroutine
def spawn_jobs():
    coros = []
    for i in range(10):
        coros.append(asyncio.Task(do_work()))
    yield from asyncio.gather(*coros)

if __name__ == '__main__':
    loop = asyncio.get_event_loop()
    loop.create_task(display_status())
    loop.run_until_complete(spawn_jobs())
    loop.close()

我希望无论 do_work() 协程做什么，计数器都会每秒打印到控制台。但我只有两个输出：0 和几秒钟后重复 10。

Answer 1

但我只有两个输出：0 和几秒钟后重复 10。

我无法重现它。如果我使用：

import asyncio
import random

@asyncio.coroutine
def do_work():
    global COUNTER
    yield from asyncio.sleep(random.randint(1, 5))
    COUNTER += 1

我得到这样的输出：

0
0
4
6
8
Task was destroyed but it is pending!
task: <Task pending coro=<display_status() running at most_wanted.py:16> wait_for=<Future pending cb=[Task._wakeup()] created at ../Lib/asyncio/tasks.py:490> created at most_wanted.py:27>

无限循环在最后display_status()导致警告。避免警告；当批处理中的所有任务完成时退出循环：

#!/usr/bin/env python3
import asyncio
import random
from contextlib import closing
from itertools import cycle

class Batch:
    def __init__(self, n):
        self.total = n
        self.done = 0

    async def run(self):
        await asyncio.wait([batch.do_work() for _ in range(batch.total)])

    def running(self):
        return self.done < self.total

    async def do_work(self):
        await asyncio.sleep(random.randint(1, 5)) # do some work here
        self.done += 1

    async def display_status(self):
        while self.running():
            await asyncio.sleep(1)
            print('\rdone:', self.done)

    async def display_spinner(self, char=cycle('/|\-')):
        while self.running():
            print('\r' + next(char), flush=True, end='')
            await asyncio.sleep(.3)

with closing(asyncio.get_event_loop()) as loop:
    batch = Batch(10)
    loop.run_until_complete(asyncio.wait([
        batch.run(), batch.display_status(), batch.display_spinner()]))

输出

done: 0
done: 2
done: 3
done: 4
done: 10