Python使用asyncio实现异步操作的示例

import asyncio

async def fetch_data():
    print("Fetching data...")
    await asyncio.sleep(2)  # 模拟耗时的 I/O 操作，如数据库查询或API请求
    return {"data": "sample"}

async def main():
    data = await fetch_data()
    print(data)

# 运行事件循环
asyncio.run(main())

import asyncio


async def task_1():
    await asyncio.sleep(5)
    return "Task 1 finished"


async def task_2():
    await asyncio.sleep(5)
    return "Task 2 finished"


async def main():
    # 计算运行耗时
    start_time = asyncio.get_running_loop().time()
    results = await asyncio.gather(task_1(), task_2())
    print(f"Total time: {asyncio.get_running_loop().time() - start_time}")
    print(results)


asyncio.run(main())

import asyncio


async def task_1():
    await asyncio.sleep(2)
    return "Task 1 complete"


async def task_2():
    await asyncio.sleep(1)
    return "Task 2 complete"


async def main():
    # 计算运行的时间
    start_time = asyncio.get_running_loop().time()
    t1 = asyncio.create_task(task_1())
    t2 = asyncio.create_task(task_2())

    await t1  # 等待任务1完成
    await t2  # 等待任务2完成

    print(asyncio.get_running_loop().time() - start_time)
    print(t1.result())
    print(t2.result())


asyncio.run(main())

async def risky_task():
    await asyncio.sleep(1)
    raise ValueError("An error occurred!")

async def main():
    try:
        await risky_task()
    except ValueError as e:
        print(f"Caught exception: {e}")

asyncio.run(main())

async def long_task():
    await asyncio.sleep(5)
    return "Task finished"

async def main():
    try:
        result = await asyncio.wait_for(long_task(), timeout=2)
        print(result)
    except asyncio.TimeoutError:
        print("Task timed out")

asyncio.run(main())

import asyncio

async def fetch_data_from_api():
    print("Fetching data from API...")
    await asyncio.sleep(3)  # 模拟 API 请求
    return {"api_data": "some api data"}

async def read_from_file():
    print("Reading data from file...")
    await asyncio.sleep(2)  # 模拟文件读操作
    return "file content"

async def write_to_db(data):
    print(f"Writing {data} to database...")
    await asyncio.sleep(1)  # 模拟数据库写入操作
    return "DB write success"

async def main():
    # 并发执行 I/O 操作
    api_task = asyncio.create_task(fetch_data_from_api())
    file_task = asyncio.create_task(read_from_file())

    # 等待所有 I/O 操作完成
    api_data, file_content = await asyncio.gather(api_task, file_task)

    # 处理 I/O 操作的结果
    print(f"API Data: {api_data}")
    print(f"File Content: {file_content}")

    # 写入数据库
    db_result = await write_to_db(api_data)
    print(db_result)

asyncio.run(main())