无异步操作代码

利用time.sleep使得线程挂起，模拟阻塞运行。

async def hello(x):
    print(x,'Hello World:%s' % time.time())
    time.sleep(1)
    print(x,'Hello World:%s' % time.time())

def run():
    print(time.time())
    tasks = [asyncio.ensure_future(hello(1)),
            asyncio.ensure_future(hello(2)),
            asyncio.ensure_future(hello(3)),
            asyncio.ensure_future(hello(4)),
            asyncio.ensure_future(hello(5)),]
    loop.run_until_complete(asyncio.wait(tasks))

if __name__ =='__main__':
    loop = asyncio.get_event_loop()
    run() 
    print('123')

异步操作代码

用asyncio.sleep模拟异步阻塞运行。

async def hello(x):
    print(x,'Hello World:%s' % time.time())
    await asyncio.sleep(1)
    print(x,'Hello World:%s' % time.time())

def run():
    print(time.time())
    tasks = [asyncio.ensure_future(hello(1)),
            asyncio.ensure_future(hello(2)),
            asyncio.ensure_future(hello(3)),
            asyncio.ensure_future(hello(4)),
            asyncio.ensure_future(hello(5)),]
    loop.run_until_complete(asyncio.wait(tasks))

if __name__ =='__main__':
    loop = asyncio.get_event_loop()
    run() 
    print('123')

执行结果

无异步

异步

结论

异步操作可以在程序执行到阻塞任务时，释放权限执行下一个任务，这样就可以缩短程序运行的时间。