关于asyncio的ValueError: too many file descriptors in select()错误

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最近写爬虫用asyncio+aiohttp的形式，代码如下：

import aiohttp
import asyncioheaders = {"Upgrade-Insecure-Requests": "1","User-Agent": "Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/58.0.3029.110 Safari/537.36","Accept": "text/html,application/xhtml+xml,application/xml;q=0.9,image/webp,*/*;q=0.8","Accept-Encoding": "gzip, deflate, sdch, br","Accept-Language": "zh-CN,zh;q=0.8",}async def ss(url):async with aiohttp.ClientSession() as session:async with session.get(url,headers=headers) as resp:print(resp.status)d = (await resp.text("utf-8","ignore"))cc(d)def cc(v):print(v)soup = BeautifulSoup(v, "lxml")contents = soup.select("div.content")for conten in contents:articleAuthor = conten.select("div.blog_info > a")if articleAuthor:# print(articleAuthor)articleAuthor = articleAuthor[0]else:articleAuthor = ""print(articleAuthor)loop = asyncio.get_event_loop()
tasks = [ss(url) for url in ["http://www.iteye.com/blogs/tag/java?page="+str(x) for x in range(1,2)] ]
loop.run_until_complete(asyncio.gather(*tasks))

乍一看代码没有问题，运行起来代码也没有问题，但是如果将url增加到上千个就会报ValueError: too many file descriptors in select()的错误

这是为什么呢？

因为asyncio内部用到了select，而select就是那个什么系统打开文件数是有限度的，上面的代码一次性将处理url的函数作为任务扔进了一个超大的List中，这就引起了错误，用这种形式无法写大规模爬虫

那怎么办呢？

用回调

代码如下：

from bs4 import BeautifulSoup
import aiohttp
import asyncio
import timeurlss=[]
headers = {"Upgrade-Insecure-Requests": "1","User-Agent": "Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/58.0.3029.110 Safari/537.36","Accept": "text/html,application/xhtml+xml,application/xml;q=0.9,image/webp,*/*;q=0.8","Accept-Encoding": "gzip, deflate, sdch, br","Accept-Language": "zh-CN,zh;q=0.8",}async def ss(url):async with aiohttp.ClientSession() as session:async with session.get(url,headers=headers) as resp:print(resp.status)return await resp.text("utf-8","ignore")def cc(v):print("ssssssss")# print(v.result())# result()获取内容soup = BeautifulSoup(v.result(), "lxml")contents = soup.select("div.content")for conten in contents:# articleAuthor = conten.select("div.blog_info > a")# if articleAuthor:#     # print(articleAuthor)#     articleAuthor = articleAuthor[0]# else:#     articleAuthor = ""articleUrl = conten.select("h3 > a")if articleUrl:articleUrl = articleUrl[0].get("href")urlss.append(articleUrl)# async def ss2(url):
#     async with aiohttp.ClientSession() as session:
#         async with session.get(url,headers=headers) as resp:
#             print(resp.status)
#             return await resp.text("utf-8","ignore")def cc2(v):print("ssssssss222222222222")# print(v.result())# result()获取内容soup = BeautifulSoup(v.result(), "lxml")articleImages_list = soup.select("img")if articleImages_list:articleImages_list = articleImages_list[0].get("src")else:articleImages_list = []print(articleImages_list)now = lambda: time.time()
start = now()
loop = asyncio.get_event_loop()# url = "http://www.iteye.com/blogs/tag/java?page=1"
for url in ["http://www.iteye.com/blogs/tag/java?page="+str(x) for x in range(1,2)]:coroutine = ss(url)# 添加任务task = asyncio.ensure_future(coroutine)# 回调task.add_done_callback(cc)# 事件循环loop.run_until_complete(task)for url in urlss:coroutine = ss(url)task = asyncio.ensure_future(coroutine)task.add_done_callback(cc2)loop.run_until_complete(task)print('TIME: ', now() - start)

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