前言

ClientTimeout 是设置整个会话的超时时间，默认情况下是300秒（5分钟）超时。

ClientTimeout

默认情况下，aiohttp使用总共300 秒（5 分钟）超时，这意味着整个操作应该在 5 分钟内完成。

timeout = aiohttp.ClientTimeout(total=60) async with aiohttp.ClientSession(timeout=timeout) as session: ... 

对于如下对session会话发单个请求，超时可能会被覆盖ClientSession.get()：

讯享网async with session.get(url, timeout=timeout) as resp: ... 

ClientTimeout 可以支持的字段

• total 整个操作的最大秒数，包括建立连接、发送请求和读取响应。
• connect 如果超出池连接限制，则建立新连接或等待池中的空闲连接的最大秒数。
• sock_connect 为新连接连接到对等点的最大秒数，不是从池中给出的。
• sock_read 从对等点读取新数据部分之间允许的最大秒数。

默认超时为：

aiohttp.ClientTimeout(total=5*60, connect=None, sock_connect=None, sock_read=None) 

讯享网

实例

讯享网import aiohttp import asyncio from pathlib import Path async def down_img(session, url): """下载图片""" name = url.split('/')[-1] # 获得图片名字 img = await session.get(url) # 触发到await就切换，等待get到数据 content = await img.read() # 读取内容 with open('./down_img/'+str(name), 'wb') as f: # 写入至文件 f.write(content) print(f'{name} 下载完成！') return str(url) async def main(URL): # 建立会话session timeout = aiohttp.ClientTimeout(total=3) conn = aiohttp.TCPConnector(ssl=False) # 防止ssl报错 async with aiohttp.ClientSession(timeout=timeout, connector=conn) as session: # 建立所有任务 tasks = [asyncio.create_task(down_img(session, img_url)) for img_url in URL] # 触发await，等待任务完成 done, pending = await asyncio.wait(tasks) # all_results = [done_task.result() for done_task in done] # # 获取所有结果 # print("ALL RESULT:"+str(all_results)) URL = [ 'https://cdn.pixabay.com/photo/2014/10/07/13/48/mountain-_960_720.jpg', 'https://cdn.pixabay.com/photo/2013/07/18/10/56/railroad-_960_720.jpg', 'https://cdn.pixabay.com/photo/2018/03/12/20/07/maldives-_960_720.jpg', 'https://cdn.pixabay.com/photo/2017/08/04/17/56/dolomites-_960_720.jpg', 'https://cdn.pixabay.com/photo/2016/06/20/03/15/pier-_960_720.jpg', 'https://cdn.pixabay.com/photo/2014/07/30/02/00/iceberg-_960_720.jpg', 'https://cdn.pixabay.com/photo/2014/11/02/10/41/plane-_960_720.jpg', 'https://cdn.pixabay.com/photo/2015/10/30/20/13/sea-_960_720.jpg', 'https://cdn.pixabay.com/photo/2014/10/07/13/48/mountain-_960_720.jpg', 'https://cdn.pixabay.com/photo/2013/07/18/10/56/railroad-_960_720.jpg', ] fp = Path('./down_img') if not fp.exists(): fp.mkdir() loop = asyncio.get_event_loop() loop.run_until_complete(main(URL)) 

由于3秒内没完成所有的请求，运行结果会抛出异常：asyncio.TimeoutError

sea-_960_720.jpg 下载完成！ railroad-_960_720.jpg 下载完成！ plane-_960_720.jpg 下载完成！ iceberg-_960_720.jpg 下载完成！ Task exception was never retrieved future: <Task finished name='Task-2' coro=<down_img() done, defined at D:/demo/demo/new/xuexi/d1.py:6> exception=TimeoutError()> Traceback (most recent call last): File "D:/demo/demo/new/xuexi/d1.py", line 12, in down_img content = await img.read() ... raise asyncio.TimeoutError from None asyncio.exceptions.TimeoutError 

给单个请求添加timeout

如果我们的需求是每个请求设置超时，单个请求大于3秒就超时，把timeout参数放到get请求上

讯享网 timeout = aiohttp.ClientTimeout(total=3) img = await session.get(url, timeout=timeout) 

完整的代码

import aiohttp import asyncio from pathlib import Path async def down_img(session, url): """下载图片""" name = url.split('/')[-1] # 获得图片名字 timeout = aiohttp.ClientTimeout(total=3) img = await session.get(url, timeout=timeout) # 触发到await就切换，等待get到数据 content = await img.read() # 读取内容 with open('./down_img/'+str(name), 'wb') as f: # 写入至文件 f.write(content) print(f'{name} 下载完成！') return str(url) async def main(URL): # 建立会话session conn = aiohttp.TCPConnector(ssl=False) # 防止ssl报错 async with aiohttp.ClientSession(connector=conn) as session: # 建立所有任务 tasks = [asyncio.create_task(down_img(session, img_url)) for img_url in URL] # 触发await，等待任务完成 done, pending = await asyncio.wait(tasks) # all_results = [done_task.result() for done_task in done] # # 获取所有结果 # print("ALL RESULT:"+str(all_results)) URL = [ 'https://cdn.pixabay.com/photo/2014/10/07/13/48/mountain-_960_720.jpg', 'https://cdn.pixabay.com/photo/2013/07/18/10/56/railroad-_960_720.jpg', 'https://cdn.pixabay.com/photo/2018/03/12/20/07/maldives-_960_720.jpg', 'https://cdn.pixabay.com/photo/2017/08/04/17/56/dolomites-_960_720.jpg', 'https://cdn.pixabay.com/photo/2016/06/20/03/15/pier-_960_720.jpg', 'https://cdn.pixabay.com/photo/2014/07/30/02/00/iceberg-_960_720.jpg', 'https://cdn.pixabay.com/photo/2014/11/02/10/41/plane-_960_720.jpg', 'https://cdn.pixabay.com/photo/2015/10/30/20/13/sea-_960_720.jpg', 'https://cdn.pixabay.com/photo/2014/10/07/13/48/mountain-_960_720.jpg', 'https://cdn.pixabay.com/photo/2013/07/18/10/56/railroad-_960_720.jpg', ] fp = Path('./down_img') if not fp.exists(): fp.mkdir() loop = asyncio.get_event_loop() loop.run_until_complete(main(URL)) 

这样写其实并不会达到我们的预期，官方文档上说对于如下请求，超时可能会被覆盖ClientSession.get()

那你timeout不管放在ClientSession() 还是单个get/post请求里，其实效果都一样，都是针对整个会话超时。

捕获超时异常 asyncio.TimeoutError

触发的超时异常是 asyncio.TimeoutError，从Traceback可以看到是content = await img.read() 这里报错

讯享网import aiohttp import asyncio from pathlib import Path async def down_img(session, url): """下载图片""" name = url.split('/')[-1] # 获得图片名字 try: img = await session.get(url) # 触发到await就切换，等待get到数据 content = await img.read() # 读取内容 with open('./down_img/'+str(name), 'wb') as f: # 写入至文件 f.write(content) print(f'{name} 下载完成！') return str(url) except asyncio.TimeoutError as msg: print('timeout: '+str(url)) return str(url) async def main(URL): # 建立会话session timeout = aiohttp.ClientTimeout(total=3) conn = aiohttp.TCPConnector(ssl=False) # 防止ssl报错 async with aiohttp.ClientSession(timeout=timeout, connector=conn) as session: # 建立所有任务 tasks = [asyncio.create_task(down_img(session, img_url)) for img_url in URL] # 触发await，等待任务完成 done, pending = await asyncio.wait(tasks) # all_results = [done_task.result() for done_task in done] # # 获取所有结果 # print("ALL RESULT:"+str(all_results)) URL = [ 'https://cdn.pixabay.com/photo/2014/10/07/13/48/mountain-_960_720.jpg', 'https://cdn.pixabay.com/photo/2013/07/18/10/56/railroad-_960_720.jpg', 'https://cdn.pixabay.com/photo/2018/03/12/20/07/maldives-_960_720.jpg', 'https://cdn.pixabay.com/photo/2017/08/04/17/56/dolomites-_960_720.jpg', 'https://cdn.pixabay.com/photo/2016/06/20/03/15/pier-_960_720.jpg', 'https://cdn.pixabay.com/photo/2014/07/30/02/00/iceberg-_960_720.jpg', 'https://cdn.pixabay.com/photo/2014/11/02/10/41/plane-_960_720.jpg', 'https://cdn.pixabay.com/photo/2015/10/30/20/13/sea-_960_720.jpg', 'https://cdn.pixabay.com/photo/2014/10/07/13/48/mountain-_960_720.jpg', 'https://cdn.pixabay.com/photo/2013/07/18/10/56/railroad-_960_720.jpg', ] fp = Path('./down_img') if not fp.exists(): fp.mkdir() loop = asyncio.get_event_loop() loop.run_until_complete(main(URL)) 

运行结果:

plane-_960_720.jpg 下载完成！ maldives-_960_720.jpg 下载完成！ sea-_960_720.jpg 下载完成！ dolomites-_960_720.jpg 下载完成！ iceberg-_960_720.jpg 下载完成！ mountain-_960_720.jpg 下载完成！ timeout: https://cdn.pixabay.com/photo/2013/07/18/10/56/railroad-_960_720.jpg timeout: https://cdn.pixabay.com/photo/2016/06/20/03/15/pier-_960_720.jpg timeout: https://cdn.pixabay.com/photo/2013/07/18/10/56/railroad-_960_720.jpg timeout: https://cdn.pixabay.com/photo/2014/10/07/13/48/mountain-_960_720.jpg