如何使用python请求执行限时响应下载? [英] How to perform time limited response download with python requests?

问题描述

在用python下载大文件的时候，我不仅要对连接过程设置时间限制，还要对下载设置时间限制.

When downloading a large file with python, I want to put a time limit not only for the connection process, but also for the download.

我正在尝试使用以下 python 代码:

I am trying with the following python code:

import requests

r = requests.get('http://ipv4.download.thinkbroadband.com/1GB.zip', timeout = 0.5, prefetch = False)

print r.headers['content-length']

print len(r.raw.read())

这不起作用(下载没有时间限制)，正如文档中正确指出的:https://requests.readthedocs.org/en/latest/user/quickstart/#timeouts

This does not work (the download is not time limited), as correctly noted in the docs: https://requests.readthedocs.org/en/latest/user/quickstart/#timeouts

如果可能的话，那就太好了:

This would be great if it was possible:

r.raw.read(timeout = 10)

问题是，如何设置下载时间限制?

The question is, how to put a time limit to the download?

推荐答案

答案是:不要使用请求，因为它会阻塞.使用非阻塞网络 I/O，例如 eventlet:

And the answer is: do not use requests, as it is blocking. Use non-blocking network I/O, for example eventlet:

import eventlet
from eventlet.green import urllib2
from eventlet.timeout import Timeout

url5 = 'http://ipv4.download.thinkbroadband.com/5MB.zip'
url10 = 'http://ipv4.download.thinkbroadband.com/10MB.zip'

urls = [url5, url5, url10, url10, url10, url5, url5]

def fetch(url):
    response = bytearray()
    with Timeout(60, False):
        response = urllib2.urlopen(url).read()
    return url, len(response)

pool = eventlet.GreenPool()
for url, length in pool.imap(fetch, urls):
    if (not length):
        print "%s: timeout!" % (url)
    else:
        print "%s: %s" % (url, length)

产生预期结果:

http://ipv4.download.thinkbroadband.com/5MB.zip: 5242880
http://ipv4.download.thinkbroadband.com/5MB.zip: 5242880
http://ipv4.download.thinkbroadband.com/10MB.zip: timeout!
http://ipv4.download.thinkbroadband.com/10MB.zip: timeout!
http://ipv4.download.thinkbroadband.com/10MB.zip: timeout!
http://ipv4.download.thinkbroadband.com/5MB.zip: 5242880
http://ipv4.download.thinkbroadband.com/5MB.zip: 5242880

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