Building Web Crawlers: Python Automated Data Collection Tutorials

Teach you to build an anti-blocking crawler with proxy IP by hand

Recently, a lot of friends asked Lao Zhang, why he wrote the crawler running on the run on the break? It's just like queuing up at a milk tea store, where the same IP repeatedly takes a number, and the server doesn't block you, so who does? This is the time toproxy IPto be your "diversion" now.

To give a real case: last year there is an e-commerce friends, want to pickpocket the price of competing products, the results of the company's own fixed IP catch 3 days in a row, directly by the other side of the black. Later changed into a dynamic proxy IP pool, every hour automatically change the identity of 200 times, the amount of data collection directly over 8 times.

Proxy IP real-world configuration three-piece suite

Play around with proxy IPs in Python, these are three libraries you should keep in mind:

 Classic usage of the requests library
import requests

proxies = {
    'http': 'http://user:pass@ipipgo-proxy.com:8080',
    'https': 'https://user:pass@ipipgo-proxy.com:8080'
}
response = requests.get('destination URL', proxies=proxies)

 Random proxy switching trick
from itertools import cycle
ip_pool = ipipgo.get_proxy_pool() This is a call to the ipipgo API.
proxy_cycler = cycle(ip_pool)

def get_with_retry(url).
    for _ in range(3).
        try.
            proxy = next(proxy_cycler)
            return requests.get(url, proxies=proxy)
        except Exception as e.
            print(f"{proxy} hangs, move to next")

Proxy IP Type Selection Guide

There are three main categories of proxy IPs on the market, let's use the table to speak human:

Like ipipgo's.Dynamic Residential IP PoolThe actual test in crawling a news site, 12 hours of continuous work triggered verification times less than ordinary IP 83%. their intelligent scheduling system will automatically match the optimal exit, this design is really worry-free.

Handbook on demining of common pitfalls

Three common mistakes newbies make:

1. Proxy IP used and not changed - what's the difference between wearing the same clothes and going to the bank for a week at a time?
2. Timeout settings are too dead - some sites are slow to respond when pumped, it is recommended to set a timeout of 10-15 seconds
3. Headers are not updated - remember to randomize the User-Agent as you go along, don't always use the same one!

Last week there was a student case: using free agents to capture enterprise information, the results returned are false data. Later on, he switched to ipipgo's certified agent, and the data accuracy directly soared from 47% to 99%.

Practical QA face-to-face

Q: What should I do if my proxy IP responds slowly?
A：优先检查协议类型，https代理比http通常慢200-300ms。ipipgo后台可以设置协议偏好，建议开启智能代理ip模式。

Q: How do I break the CAPTCHA when I encounter it?
A: Three-step strategy: 1) Reduce the frequency of requests 2) Switch mobile IP 3) Cooperate with the coding platform. ipipgo'sMan Machine Authentication IP PoolBuilt-in behavioral simulation algorithms, pro-tested in 12306 query scenarios CAPTCHA trigger rate reduced by 60%.

Q: How can I tell if a proxy is in effect?
A: Old Zhang's native way: print the X-Forwarded-For field in response.headers in the code to see if it's really changed the vest.

Long-lasting maintenance tips

Maintaining an agent crawler is like keeping a goldfish, you have to change the water regularly:

• Weekly update of 1/3 of the IP pool
• Doing stress tests from 2-5am
• Monitor the success rate indicator, below 90% immediately switch the channel

Lastly, don't trust those free proxies. Last year's industry report showed that 78% free proxies had data tampering. Regular service providers like ipipgo have atwo-way encrypted tunnelThe data security is really reliable, and the official website of others can also check the IP survival rate in real time, so it's safe to use.