面试题：网络编程之Python并发编程高级难度题

设计方案

连接池管理：使用aiohttp的ClientSession并配置连接池大小，以控制并发连接数，避免资源耗尽。
异步I/O操作：利用asyncio的异步特性，对文件的读写和网络请求进行异步操作，提高效率。
错误处理与重试：在网络丢包或请求失败时，实现重试机制，确保文件传输的可靠性。

关键代码片段

import asyncio
import aiohttp
import os


async def upload_file(session, file_path, server_url):
    max_retries = 3
    retries = 0
    while retries < max_retries:
        try:
            async with session.post(server_url, data=open(file_path, 'rb')) as response:
                if response.status == 200:
                    return True
                else:
                    print(f"Upload failed with status {response.status}")
        except (aiohttp.ClientError, OSError) as e:
            print(f"Upload error: {e}")
        retries += 1
        await asyncio.sleep(1)
    return False


async def download_file(session, file_path, server_url):
    max_retries = 3
    retries = 0
    while retries < max_retries:
        try:
            async with session.get(server_url) as response:
                if response.status == 200:
                    with open(file_path, 'wb') as f:
                        while True:
                            chunk = await response.content.read(1024)
                            if not chunk:
                                break
                            f.write(chunk)
                    return True
                else:
                    print(f"Download failed with status {response.status}")
        except (aiohttp.ClientError, OSError) as e:
            print(f"Download error: {e}")
        retries += 1
        await asyncio.sleep(1)
    return False


async def main():
    # 配置连接池大小，例如设置为10
    connector = aiohttp.TCPConnector(limit=10)
    async with aiohttp.ClientSession(connector=connector) as session:
        upload_tasks = []
        download_tasks = []
        # 示例上传任务
        for file in os.listdir('.'):
            if os.path.isfile(file):
                upload_tasks.append(upload_file(session, file, 'http://server/upload'))
        # 示例下载任务
        for i in range(5):
            download_tasks.append(download_file(session, f'download_{i}.txt', 'http://server/download'))
        await asyncio.gather(*upload_tasks, *download_tasks)


if __name__ == "__main__":
    asyncio.run(main())

在上述代码中：

upload_file和download_file函数分别实现了文件的上传和下载功能，在遇到错误时会进行重试。
main函数中创建了aiohttp.ClientSession并通过TCPConnector设置了连接池大小为10，以此控制并发连接数。
同时创建了多个上传和下载任务，并使用asyncio.gather并发执行这些任务。

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面试题：网络编程之Python并发编程高级难度题

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关键代码片段