[英]Why is my consumer working separately from my producer in the queue?
我的目标是异步调用 API,并将结果(来自每次调用)写入文件(1 个调用 -> 1 个文件)。 我认为实现这一点的一种方法是使用队列。 我的目的是在生产者准备好响应后立即将其推送到队列中,然后让消费者在文件可用时立即处理(写入)文件。
困惑:在我运行代码时查看打印语句,我看到首先生产者完成,然后消费者开始使用我的 output。 在 go 看来,这似乎不是我的意图,即消费者在任务可用后立即处理它们。 我也考虑过使用多个进程(1 个用于消费者,1 个用于生产者),但我不确定我是否以这种方式使事情复杂化。
我创建了当前状态的插图:
import aiohttp
import asyncio
async def get_data(session, day):
async with session.post(url=SOME_URL, json=SOME_FORMAT, headers=HEADERS) as response:
return await response.text()
async def producer(q, day):
async with aiohttp.ClientSession() as session:
result = await get_data(session, day)
await q.put(result)
async def consumer(q):
while True:
outcome = await q.get()
print("Consumed:", outcome) # assuming I write files here
q.task_done()
async def main():
queue = asyncio.Queue()
days = [day for day in range(20)] # Here I normally use calendar dates instead of range
producers = [asyncio.create_task(producer(queue, day) for day in days]
consumer = asyncio.create_task(consumer(queue)
await asyncio.gather(*producers)
await queue.join()
consumer.cancel()
if __name__ == '__main__':
asyncio.run(main())
我在正确的轨道上吗?
您的代码通常很好(除了几个语法错误,我猜这是错误的复制粘贴的结果)。 所有的生产者确实是在消费者开始工作之前创建的,因为他们没有什么可等待的。 但是,如果生产者需要做真正的工作,你会看到他们只有在消费者开始工作后才完成工作,然后事情才开始工作。
这是您的代码的编辑版本,加上 output 证明事情确实有效。
import aiohttp
import asyncio
async def get_data(session, day):
print(f"get data, day {day}")
async with session.get(url="https://www.google.com") as response:
res = await response.text()
print(f"got data, day {day}")
return res[:100]
async def producer(q, day):
async with aiohttp.ClientSession() as session:
result = await get_data(session, day)
await q.put(result)
async def consumer(q):
print("Consumer stated")
while True:
outcome = await q.get()
print("Consumed:", outcome) # assuming I write files here
asyncio.sleep(1)
q.task_done()
async def main():
queue = asyncio.Queue()
days = [day for day in range(20)] # Here I normally use calendar dates instead of range
producers = [asyncio.create_task(producer(queue, day)) for day in days]
print("main: producer tasks created")
consumer_task = asyncio.create_task(consumer(queue))
print("main: consumer task created")
await asyncio.gather(*producers)
print("main: gathered producers")
await queue.join()
consumer_task.cancel()
if __name__ == '__main__':
asyncio.run(main())
output:
main: producer tasks created
main: consumer task created
get data, day 0
get data, day 1
get data, day 2
get data, day 3
...
get data, day 19
Consumer stated
got data, day 1
Consumed: <!doctype html><html itemscope="" itemtype="http://schema.org/WebPage" lang="en"><head><meta content
queue_so.py:21: RuntimeWarning: coroutine 'sleep' was never awaited
asyncio.sleep(1)
RuntimeWarning: Enable tracemalloc to get the object allocation traceback
got data, day 10
Consumed: <!doctype html><html itemscope="" itemtype="http://schema.org/WebPage" lang="en"><head><meta content
got data, day 19
got data, day 11
got data, day 14
Consumed: <!doctype html><html itemscope="" itemtype="http://schema.org/WebPage" lang="en"><head><meta content
Consumed: <!doctype html><html itemscope="" itemtype="http://schema.org/WebPage" lang="en"><head><meta content
Consumed: <!doctype html><html itemscope="" itemtype="http://schema.org/WebPage" lang="en"><head><meta content
got data, day 15
got data, day 17
got data, day 6
got data, day 18
Consumed: <!doctype html><html itemscope="" itemtype="http://schema.org/WebPage" lang="en"><head><meta content
Consumed: <!doctype html><html itemscope="" itemtype="http://schema.org/WebPage" lang="en"><head><meta content
Consumed: <!doctype html><html itemscope="" itemtype="http://schema.org/WebPage" lang="en"><head><meta content
Consumed: <!doctype html><html itemscope="" itemtype="http://schema.org/WebPage" lang="en"><head><meta content
got data, day 7
Consumed: <!doctype html><html itemscope="" itemtype="http://schema.org/WebPage" lang="en"><head><meta content
got data, day 8
got data, day 9
got data, day 2
got data, day 12
Consumed: <!doctype html><html itemscope="" itemtype="http://schema.org/WebPage" lang="en"><head><meta content
Consumed: <!doctype html><html itemscope="" itemtype="http://schema.org/WebPage" lang="en"><head><meta content
Consumed: <!doctype html><html itemscope="" itemtype="http://schema.org/WebPage" lang="en"><head><meta content
Consumed: <!doctype html><html itemscope="" itemtype="http://schema.org/WebPage" lang="en"><head><meta content
got data, day 0
got data, day 5
Consumed: <!doctype html><html itemscope="" itemtype="http://schema.org/WebPage" lang="en"><head><meta content
Consumed: <!doctype html><html itemscope="" itemtype="http://schema.org/WebPage" lang="en"><head><meta content
got data, day 4
Consumed: <!doctype html><html itemscope="" itemtype="http://schema.org/WebPage" lang="en"><head><meta content
got data, day 3
Consumed: <!doctype html><html itemscope="" itemtype="http://schema.org/WebPage" lang="en"><head><meta content
got data, day 13
Consumed: <!doctype html><html itemscope="" itemtype="http://schema.org/WebPage" lang="en"><head><meta content
got data, day 16
Consumed: <!doctype html><html itemscope="" itemtype="http://schema.org/WebPage" lang="en"><head><meta content
main: gathered producers
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