Python asyncio.Queue 协程通信详解
本文深入解析 Python 中 asyncio.Queue 的使用,展示如何通过先进先出队列在协程间高效传递数据。通过消费者与生产者的示例代码,演示了任务调度、信号终止及异步睡眠模拟处理耗时,帮助开发者掌握异步环境下的并发通信模式。
前言
本文主要介绍 Python 中使用 asyncio.Queue 进行协程间通信的具体方法,供读者参考学习。
asyncio.Queue 遵循先进先出(FIFO)原则,专为协程环境设计。
具体实现示例如下:
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()
运行输出结果如下:
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
总结
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