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聊聊Python协程和异步编程

Python

协程和异步编程是Python/ target=_blank class=infotextkey>Python中处理并发和异步任务的重要概念 。协程是一种轻量级的并发编程方式，它允许程序在执行过程中暂停和恢复，以便处理其他任务 。异步编程模型则是基于协程的一种编程风格，它通过使用非阻塞的异步IO操作来提高程序的并发性能 。
 
Python中的异步编程主要依赖于`asyncio`模块 。`asyncio`提供了一套用于编写异步代码的工具和框架，包括协程、事件循环和异步IO操作等 。
 
代码示例：
1. 使用`async`和`awAIt`定义协程函数：
import asyncioasync def my_coroutine():await asyncio.sleep(1)print("Coroutine executed")asyncio.run(my_coroutine())2. 使用`asyncio.create_task()`并发运行多个协程：
import asyncioasync def coroutine1():await asyncio.sleep(1)print("Coroutine 1 executed")async def coroutine2():await asyncio.sleep(2)print("Coroutine 2 executed")async def main():task1 = asyncio.create_task(coroutine1())task2 = asyncio.create_task(coroutine2())await asyncio.gather(task1, task2)asyncio.run(main())3. 使用`asyncio.wait()`等待多个协程完成：
import asyncioasync def coroutine1():await asyncio.sleep(1)print("Coroutine 1 executed")async def coroutine2():await asyncio.sleep(2)print("Coroutine 2 executed")async def main():tasks = [coroutine1(), coroutine2()]done, pending = await asyncio.wait(tasks)for task in done:print(f"Task {task} completed")asyncio.run(main())4. 使用`asyncio.Lock()`实现协程间的互斥访问：
import asyncioasync def counter(lock):async with lock:for _ in range(5):print("Counting")await asyncio.sleep(1)async def main():lock = asyncio.Lock()tasks = [counter(lock) for _ in range(3)]await asyncio.gather(*tasks)asyncio.run(main())5. 使用`asyncio.Queue()`实现协程间的消息传递：
import asyncioasync def producer(queue):for i in range(5):await queue.put(i)print(f"Produced: {i}")await asyncio.sleep(1)async def consumer(queue):while True:item = await queue.get()print(f"Consumed: {item}")await asyncio.sleep(2)async def main():queue = asyncio.Queue()producer_task = asyncio.create_task(producer(queue))consumer_task = asyncio.create_task(consumer(queue))await asyncio.gather(producer_task, consumer_task)asyncio.run(main())6. 使用`asyncio.TimeoutError`设置协程的超时：
import asyncioasync def my_coroutine():await asyncio.sleep(2)print("Coroutine executed")async def main():try:await asyncio.wait_for(my_coroutine(), timeout=1)except asyncio.TimeoutError:print("Coroutine timed out")asyncio.run(main())7. 使用`asyncio.run_in_executor()`在协程中执行阻塞的同步操作：
import asynciodef sync_operation():# 阻塞的同步操作return "Sync result"async def main():loop = asyncio.get_running_loop()result = await loop.run_in_executor(None, sync_operation)print(f"Result: {result}")asyncio.run(main())8. 使用`aiohttp`库进行异步HTTP请求：
import asyncioimport aiohttpasync def fetch_data(url):async with aiohttp.ClientSession() as session:async with session.get(url) as response:return await response.text()async def main():url = "https://api.example.com/data"data = await fetch_data(url)print(f"Data: {data}")asyncio.run(main())9. 使用`asyncio.sleep()`模拟异步计时器：
import asyncioasync def timer(duration):await asyncio.sleep(duration)print(f"Timer finished after {duration} seconds")async def main():tasks = [timer(1), timer(2), timer(3)]await asyncio.gather(*tasks)asyncio.run(main())10. 使用`asyncio`实现并发的文件IO操作：
import asyncioasync def read_file(file):async with asyncio.open_file(file, "r") as f:contents = await f.read()print(f"Read from {file}: {contents}")async def write_file(file, data):async with asyncio.open_file(file, "w") as f:await f.write(data)print(f"Wrote to {file}")async def main():file = "data.txt"await write_file(file, "Hello, world!")await read_file(file)asyncio.run(main()) 这些场景代码展示了协程和异步编程的使用方式 。通过使用`asyncio`模块和相关的工具，我们可以轻松地编写并发和异步任务处理的代码，提高程序的性能和响应能力 。

【聊聊Python协程和异步编程】


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