[英]How to code consumer.producer with python asyncio?
My Python version is 3.6.1.我的 Python 版本是 3.6.1。
I wrote something to implement a model of consumer-producer with Python asyncio.我写了一些东西来使用 Python asyncio 来实现消费者生产者的 model。 But it doesn't work as expected.但它没有按预期工作。
Four events all created but none of any print export.四个事件全部创建,但没有任何打印导出。
async def consumer(queue, id):
while True:
val = await queue.get()
print('{} get a val: {}'.format(id, val))
await asyncio.sleep(1)
async def producer(queue, id):
for i in range(5):
val = random.randint(1, 10)
await queue.put(val)
print('{} put a val: {}'.format(id, val))
await asyncio.sleep(1)
async def main():
queue = asyncio.Queue()
consumer_1 = asyncio.ensure_future(consumer(queue, 'consumer_1'))
consumer_2 = asyncio.ensure_future(consumer(queue, 'consumer_2'))
producer_1 = asyncio.ensure_future(producer(queue, 'producer_1'))
producer_2 = asyncio.ensure_future(producer(queue, 'producer_2'))
await asyncio.sleep(10)
consumer_1.cancel()
consumer_2.cancel()
await asyncio.gather(consumer_1, consumer_2, producer_1, producer_2, return_exceptions=True)
loop = asyncio.get_event_loop()
tasks = [asyncio.ensure_future(main())]
loop.run_until_complete(asyncio.wait(tasks))
loop.close()
Could U please help me correct?你能帮我改正吗?
A lot of wrong things in your approach, some of those are: 您的方法中有很多错误的地方,其中包括:
asyncio.ensure_future
for producers 生产者不必要的asyncio.ensure_future
asyncio.gather
ing in arbitrary order with doubtful items 以可疑项目以任意顺序asyncio.gather
tasks = [asyncio.ensure_future(main())]
and asyncio.wait(tasks)
actions 不必要的tasks = [asyncio.ensure_future(main())]
和asyncio.wait(tasks)
操作 queue
不受控制的queue
Example of asyncio Producer/consumer scheme: https://asyncio.readthedocs.io/en/latest/producer_consumer.html 异步生产者/消费者方案的示例: https ://asyncio.readthedocs.io/en/latest/producer_consumer.html
The correct producer/consumer scheme would look as below (for your case): 正确的生产者/消费者方案如下所示(针对您的情况):
import asyncio
import random
async def consumer(queue, id):
while True:
val = await queue.get()
print('{} get a val: {}'.format(id, val))
await asyncio.sleep(1)
queue.task_done() # indicate complete task
async def producer(queue, id):
for i in range(5):
val = random.randint(1, 10)
await asyncio.sleep(1)
await queue.put(val)
print('{} put a val: {}'.format(id, val))
async def main():
queue = asyncio.Queue()
producer_1 = producer(queue, 'producer_1')
producer_2 = producer(queue, 'producer_2')
consumer_1 = asyncio.ensure_future(consumer(queue, 'consumer_1'))
consumer_2 = asyncio.ensure_future(consumer(queue, 'consumer_2'))
await asyncio.gather(*[producer_1, producer_2], return_exceptions=True)
await queue.join() # wait until the consumer has processed all items
consumer_1.cancel()
consumer_2.cancel()
loop = asyncio.get_event_loop()
loop.run_until_complete(main())
loop.close()
The output: 输出:
producer_1 put a val: 7
producer_2 put a val: 2
consumer_1 get a val: 7
consumer_2 get a val: 2
producer_1 put a val: 9
producer_2 put a val: 2
consumer_1 get a val: 9
consumer_2 get a val: 2
producer_1 put a val: 9
producer_2 put a val: 3
consumer_1 get a val: 9
consumer_2 get a val: 3
producer_1 put a val: 1
producer_2 put a val: 6
consumer_1 get a val: 1
consumer_2 get a val: 6
producer_1 put a val: 2
producer_2 put a val: 2
consumer_1 get a val: 2
consumer_2 get a val: 2
I came up with this layout as it is very clean, simple and easy to understand the asyncio code:我想出了这个布局,因为它非常干净、简单且易于理解 asyncio 代码:
import asyncio
async def producer(queue):
i = 1
while True:
await queue.put(f'item {i}')
i += 1
await asyncio.sleep(5)
async def consumer(queue):
while True:
item = await queue.get()
print(item)
if __name__ == '__main__':
queue = asyncio.Queue()
loop = asyncio.get_event_loop()
loop.create_task(producer(queue))
loop.create_task(consumer(queue))
loop.run_forever()
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