代码有点多，我都注释过了，该文章仅协程部分，python官网入门教程的化请看我github:python3.9入门教程
群：970353786
代码有点多，不懂可群问我，下面是协程方面的代码demo:
""" 作者：杨涵x 时间：2021/4/30 """ # import asyncio # async def main(): # print('Hello ...') # await asyncio.sleep(1) # print('... World!') # asyncio.run(main()) '''等待 1 秒后打印 "hello"，然后 再次 等待 2 秒后打印 "world"''' # import asyncio # import time # # async def say_after(delay, what): # await asyncio.sleep(delay) # print(what) # async def main(): # print(f"started at {time.strftime('%X')}") # await say_after(1, 'hello') # await say_after(2, 'world') # print(f"finished at {time.strftime('%X')}") # asyncio.run(main()) '''asyncio.create_task() 函数用来并发运行作为 asyncio 任务 的多个协程。''' # async def main(): # task1 = asyncio.create_task( # say_after(1, 'hello')) # task2 = asyncio.create_task( # say_after(2, 'world')) # print(f"started at {time.strftime('%X')}") # # Wait until both tasks are completed (should take # # around 2 seconds.) # await task1 # await task2 # # print(f"finished at {time.strftime('%X')}") # asyncio.run(main()) '''Python 协程属于 可等待 对象，因此可以在其他协程中被等待''' # import asyncio # # async def nested(): # return 42 # # async def main(): # # Nothing happens if we just call "nested()". # # A coroutine object is created but not awaited, # # so it *won't run at all*. # # Let's do it differently now and await it: # print(await nested()) # will print "42". # # asyncio.run(main()) ''' 协程函数: 定义形式为 async def 的函数; 协程对象: 调用 协程函数 所返回的对象。 ''' '''当一个协程通过 asyncio.create_task() 等函数被封装为一个 任务，该协程会被自动调度执行''' # import asyncio # # async def nested(): # return 42 # # async def main(): # # Schedule nested() to run soon concurrently # # with "main()". # task = asyncio.create_task(nested()) # # # "task" can now be used to cancel "nested()", or # # can simply be awaited to wait until it is complete: # await task # asyncio.run(main()) '''运行 asyncio 程序''' '''asyncio.run(coro, *, debug=False)¶''' # import asyncio # async def main(): # await asyncio.sleep(1) # print('hello') # # asyncio.run(main()) '''创建任务''' '''asyncio.create_task(coro, *, name=None)¶''' # import asyncio # async def coro(): # return 2021 # task = asyncio.create_task(coro())#python3.7+ # This works in all Python versions but is less readable # task = asyncio.ensure_future(coro())#before python3.7 '''休眠''' ''' asyncio.sleep(delay, result=None, *, loop=None)¶''' '''以下协程示例运行 5 秒，每秒显示一次当前日期''' # import asyncio # import datetime # # async def display_date(): # loop = asyncio.get_running_loop() # end_time = loop.time() + 5.0 # while True: # print(datetime.datetime.now()) # if (loop.time() + 1.0) >= end_time: # break # await asyncio.sleep(1) # # asyncio.run(display_date()) '''并发运行任务''' ''' asyncio.gather(*aws, loop=None, return_exceptions=False)¶''' # import asyncio # # async def factorial(name, number): # f = 1 # for i in range(2, number + 1): # print(f"Task {name}: Compute factorial({i})...") # await asyncio.sleep(1) # f *= i # print(f"Task {name}: factorial({number}) = {f}") # # async def main(): # # Schedule three calls *concurrently*: # await asyncio.gather( # factorial("A", 2), # factorial("B", 3), # factorial("C", 4), # ) # # asyncio.run(main()) '''屏蔽取消操作''' '''asyncio.shield(aw, *, loop=None)保护一个 可等待对象 防止其被 取消''' # res = await shield(something())#demo '''如果希望完全忽略取消操作 (不推荐) 则 shield() 函数需要配合一个 try/except 代码段''' # try: # res = await shield(something()) # except CancelledError: # res = None '''超时''' '''asyncio.wait_for(aw, timeout, *, loop=None)¶''' # import asyncio # async def eternity(): # # Sleep for one hour # await asyncio.sleep(3600) # print('yay!') # # async def main(): # # Wait for at most 1 second # try: # await asyncio.wait_for(eternity(), timeout=1.0) # except asyncio.TimeoutError: # print('timeout!') # # asyncio.run(main()) '''简单等待''' '''syncio.wait(aws, *, loop=None, timeout=None, return_when=ALL_COMPLETED)''' # 用法: # import asyncio # done, pending = await asyncio.wait(aws) # async def foo(): # return 42 # # task = asyncio.create_task(foo()) # done, pending = await asyncio.wait({task}) # # if task in done: # asyncio.run(task) # # Everything will work as expected now. '''在线程中运行''' '''asyncio.to_thread(func, /, *args, **kwargs)在不同的线程中异步地运行函数 func。''' '''这个协程函数主要是用于执行在其他情况下会阻塞事件循环的 IO 密集型函数/方法''' # import asyncio,time # def blocking_io(): # print(f"start blocking_io at {time.strftime('%X')}") # # Note that time.sleep() can be replaced with any blocking # # IO-bound operation, such as file operations. # time.sleep(1) # print(f"blocking_io complete at {time.strftime('%X')}") # # async def main(): # print(f"started main at {time.strftime('%X')}") # # await asyncio.gather( # asyncio.to_thread(blocking_io), # asyncio.sleep(1)) # print(f"finished main at {time.strftime('%X')}") # asyncio.run(main()) ''':要取消一个正在运行的 Task 对象可使用 cancel() 方法。调用此方法将使该 Task 对象抛出一个 CancelledError 异常给打包的协程''' '''以下示例演示了协程是如何侦听取消请求的''' # import asyncio # async def cancel_me(): # print('cancel_me(): before sleep') # # try: # # Wait for 1 hour # await asyncio.sleep(3600) # except asyncio.CancelledError: # print('cancel_me(): cancel sleep') # raise # finally: # print('cancel_me(): after sleep') # # async def main(): # # Create a "cancel_me" Task # task = asyncio.create_task(cancel_me()) # # # Wait for 1 second # await asyncio.sleep(1) # # task.cancel() # try: # await task # except asyncio.CancelledError: # print("main(): cancel_me is cancelled now") # # asyncio.run(main()) '''基于生成器的协程''' '''@asyncio.coroutine 用来标记基于生成器的协程的装饰器。 此装饰器使得旧式的基于生成器的协程能与 async/await 代码相兼容 ''' # import asyncio # @asyncio.coroutine # def old_style_coroutine(): # yield from asyncio.sleep(1) # # async def main(): # await old_style_coroutine() '''队列能被用于多个的并发任务的工作量分配：''' import asyncio import random import time async def worker(name, queue): while True: # Get a "work item" out of the queue. sleep_for = await queue.get() # Sleep for the "sleep_for" seconds. await asyncio.sleep(sleep_for) # Notify the queue that the "work item" has been processed. queue.task_done() print(f'{name} has slept for {sleep_for:.2f} seconds') async def main(): # Create a queue that we will use to store our "workload". queue = asyncio.Queue() # Generate random timings and put them into the queue. total_sleep_time = 0 for _ in range(20): sleep_for = random.uniform(0.05, 1.0) total_sleep_time += sleep_for queue.put_nowait(sleep_for) # Create three worker tasks to process the queue concurrently. tasks = [] for i in range(3): task = asyncio.create_task(worker(f'worker-{i}', queue)) tasks.append(task) # Wait until the queue is fully processed. started_at = time.monotonic() await queue.join() total_slept_for = time.monotonic() - started_at # Cancel our worker tasks. for task in tasks: task.cancel() # Wait until all worker tasks are cancelled. await asyncio.gather(*tasks, return_exceptions=True) print('====') print(f'3 workers slept in parallel for {total_slept_for:.2f} seconds') print(f'total expected sleep time: {total_sleep_time:.2f} seconds') asyncio.run(main())
