python异步调用exe等待_Python中最简单的异步/等待示例

is it possible to give a simple example showing how async / await

works, by using only these two keywords + asyncio.get_event_loop() +

run_until_complete + other Python code but no other asyncio functions?

这样就可以编写有效的代码：

import asyncio

async def main():

print('done!')

if __name__ == '__main__':

loop = asyncio.get_event_loop()

loop.run_until_complete(main())

但这样就无法证明为什么需要asyncio.

顺便说一句,为什么你需要asyncio,而不仅仅是简单的代码？答案是 – 当您并行化I / O阻塞操作(如读/写网络)时,asyncio允许您获得性能优势.要编写有用的示例,您需要使用这些操作的异步实现.

有关详细说明,请阅读this answer.

UPD：

好的,这是使用asyncio.sleep来模仿I / O阻塞操作的示例,以及asyncio.gather,它显示了如何同时运行多个阻塞操作：

import asyncio

async def io_related(name):

print(f'{name} started')

await asyncio.sleep(1)

print(f'{name} finished')

async def main():

await asyncio.gather(

io_related('first'),

io_related('second'),

) # 1s + 1s = over 1s

if __name__ == '__main__':

loop = asyncio.get_event_loop()

loop.run_until_complete(main())

输出：

first started

second started

first finished

second finished

[Finished in 1.2s]

注意两个io_related如何在一秒钟之后开始,两者都完成了.