编写多线程爬虫(线程数量4个)爬取豆瓣网站人文标签下所有书籍(至少爬取前10页)的信息(包括书名、作者、出版社、出版日期、页数、价格、ISBN号、豆瓣评分、评价人数、书籍封面、URL)，并按照豆瓣评分降序保存(以标签名称命名),并把爬取到的信息保存在一个csv文件中

好的，这是一个比较复杂的任务，需要使用多个第三方库和技术，包括requests、BeautifulSoup、Pandas、threading等。下面是一个简单的代码示例，仅供参考：

import requests
from bs4 import BeautifulSoup
import pandas as pd
import threading

class BookScraper(threading.Thread):
    def __init__(self, url, tag):
        super(BookScraper, self).__init__()
        self.url = url
        self.tag = tag

    def run(self):
        self.books = []
        for page in range(0, 10):
            url = self.url + '?start=' + str(page*20) + '&type=T'
            response = requests.get(url)
            soup = BeautifulSoup(response.text, 'html.parser')
            items = soup.find_all('li', class_='subject-item')
            for item in items:
                book = {}
                book['tag'] = self.tag
                book['title'] = item.find('div', class_='info').h2.a.text.strip()
                book['author'] = item.find('div', class_='pub').text.split('/')[0].strip()
                book['publisher'] = item.find('div', class_='pub').text.split('/')[-3].strip()
                book['publish_date'] = item.find('div', class_='pub').text.split('/')[-2].strip()
                book['page_num'] = item.find('div', class_='pub').text.split('/')[-1].strip()
                book['price'] = item.find('div', class_='pub').text.split('/')[-4].strip()
                book['ISBN'] = item.find('div', class_='pl').text.strip().split(':')[1].strip()
                book['rating'] = item.find('span', class_='rating_nums').text.strip()
                book['rating_num'] = item.find('span', class_='pl').text.strip().split('(')[1].split('人评价')[0].strip()
                book['image'] = item.find('img')['src']
                book['url'] = item.find('div', class_='pic').a['href']
                self.books.append(book)

    def get_books(self):
        return self.books

def save_to_csv(tag, books):
    df = pd.DataFrame(books)
    df.sort_values(by='rating', ascending=False, inplace=True)
    filename = tag + '.csv'
    df.to_csv(filename, index=False)

if __name__ == '__main__':
    tags = ['文化', '历史', '社会学', '心理学', '哲学']
    urls = ['https://book.douban.com/tag/' + tag for tag in tags]
    threads = []
    for i in range(len(tags)):
        thread = BookScraper(urls[i], tags[i])
        threads.append(thread)
        thread.start()

    for thread in threads:
        thread.join()
        tag = thread.tag
        books = thread.get_books()
        save_to_csv(tag, books)

注意，此代码仅供参考，实际爬取过程中还需要处理异常、反爬虫等问题。同时，由于豆瓣网的反爬虫措施比较严格，如果爬取速度过快或者爬取量过大，可能会被封禁IP，请谨慎使用。