python里使用队列asyncio.Queue进行通讯

最新推荐文章于 2023-08-25 09:42:48 发布

caimouse

最新推荐文章于 2023-08-25 09:42:48 发布

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分类专栏： milang(小语）文章标签： asyncio python tensorflow

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本文通过一个具体的示例介绍了Python中asyncio.Queue的用法，包括如何创建队列、添加任务以及停止信号的处理方式。该示例展示了多个消费者和生产者如何协同工作。

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asyncio.Queue与其它队列是一样的，都是先进先出，它是为协程定义的，例子如下：

import asyncio


async def consumer(n, q):
    print('consumer {}: starting'.format(n))
    while True:
        print('consumer {}: waiting for item'.format(n))
        item = await q.get()
        print('consumer {}: has item {}'.format(n, item))
        if item is None:
            # None is the signal to stop.
            q.task_done()
            break
        else:
            await asyncio.sleep(0.01 * item)
            q.task_done()
    print('consumer {}: ending'.format(n))


async def producer(q, num_workers):
    print('producer: starting')
    # Add some numbers to the queue to simulate jobs
    for i in range(num_workers * 3):
        await q.put(i)
        print('producer: added task {} to the queue'.format(i))
    # Add None entries in the queue
    # to signal the consumers to exit
    print('producer: adding stop signals to the queue')
    for i in range(num_workers):
        await q.put(None)
    print('producer: waiting for queue to empty')
    await q.join()
    print('producer: ending')


async def main(loop, num_consumers):
    # Create the queue with a fixed size so the producer
    # will block until the consumers pull some items out.
    q = asyncio.Queue(maxsize=num_consumers)

    # Scheduled the consumer tasks.
    consumers = [
        loop.create_task(consumer(i, q))
        for i in range(num_consumers)
    ]

    # Schedule the producer task.
    prod = loop.create_task(producer(q, num_consumers))

    # Wait for all of the coroutines to finish.
    await asyncio.wait(consumers + [prod])


event_loop = asyncio.get_event_loop()
try:
    event_loop.run_until_complete(main(event_loop, 2))
finally:
    event_loop.close()

输出如下：

consumer 0: starting
consumer 0: waiting for item
consumer 1: starting
consumer 1: waiting for item
producer: starting
producer: added task 0 to the queue
producer: added task 1 to the queue
consumer 0: has item 0
consumer 1: has item 1
producer: added task 2 to the queue
producer: added task 3 to the queue
consumer 0: waiting for item
consumer 0: has item 2
producer: added task 4 to the queue
consumer 1: waiting for item
consumer 1: has item 3
producer: added task 5 to the queue
producer: adding stop signals to the queue
consumer 0: waiting for item
consumer 0: has item 4
consumer 1: waiting for item
consumer 1: has item 5
producer: waiting for queue to empty
consumer 0: waiting for item
consumer 0: has item None
consumer 0: ending
consumer 1: waiting for item
consumer 1: has item None
consumer 1: ending
producer: ending