Cloud-Based Web Crawling: Distributed Crawling Solutions

Teach you to build a cloud crawler with proxy IP by hand

Recently, many friends who do data collection have come to ask me why the crawler they write is alwaysIP blocked by websiteThe first thing you need to do is to get the same IP address as the one you are using. In fact, this thing with the game hang a reason, you always use the same IP crazy request, the site is not a fool. At this time it is time to offer a distributed crawler + proxy IP of the golden combination.

The Three Deadliest Points of Traditional Crawlers

Let's start by dishing out a few potholes where the average reptile has fallen head over heels:
1. Stand-alone IPs are easily blocked (the worst I've ever seen was blacked out in 5 minutes)
2. Capture at a turtle's pace (especially when large amounts of data are required)
3. The anti-climbing mechanism is a dead giveaway

Last year to help friends engage in e-commerce price comparison project, they wrote their own crawler every hour was blocked more than 20 IP, and finally rely on proxy IP to save the day. Here a word of advice, choose a proxy IP must not be greedy for cheap, some free proxy response speed can be out of white hair.

The right way to open a distributed crawler

Engaging in distributed crawling is, to put it bluntlyMultiple machines + different IPsCollaboration. Here's a real-world configuration scenario:

 Python Sample Code
import requests
from multiprocessing import Pool

def crawler(url): { url = { url
    proxies = {
        "http": "http://username:password@gateway.ipipgo.com:9020",
        "https": "http://username:password@gateway.ipipgo.com:9020"
    }
    try.
        resp = requests.get(url, proxies=proxies, timeout=10)
        return resp.text
    except Exception as e.
        print(f "Capture failed: {str(e)}")

if __name__ == '__main__': urls = [...].
    urls = [...]  List of links to be collected
    with Pool(10) as p: 10 processes concurrently
        results = p.map(crawler, urls)

Note the proxy configuration in the code, which is used hereipipgoof enterprise-level agency services. One good thing about their home is that they supportDynamic session hold, especially suitable for collection scenarios that require login status.

Proxy IP Selection Guide to Avoid Pitfalls

There are all sorts of agency services on the market, so let's put together a comparison table for the guys:

Here's the kicker.ipipgoThe intelligent routing function. This thing can automatically switch the optimal node, the last time to do the national house price collection, the same task in different areas with different IP, the success rate directly from 60% soared to 95%.

First aid kit for real-world problems

Q: What should I do if my proxy IP suddenly fails?
A: Select Yesreal time monitoringservice providers, such as ipipgo background can see the health status of each IP. It is recommended that a retry mechanism be added to the code to automatically replace failed IPs when they are encountered.

Q: How can I improve my collection efficiency?
A: Remember the formula:Concurrency = Number of available IPs × 2. For example, there are 50 IP, open 100 threads is more appropriate. But be careful to set the request interval, don't make people's websites go down.

Q: Is it legal to collect data?
A: focus on three points: 1. comply with the robots agreement 2. do not touch the user's private data 3. control the frequency of requests. It is recommended to match ipipgo'sIntelligent regulation of request frequencyFunctions to automatically adapt anti-crawl strategies for different websites.

Speak from the heart.

Being in the crawler business for more than five years, I've seen too many people fall on proxy IPs. Some friends in order to save some money, the result spend more time to deal with the problem of IP blocking. Since the use ofipipgoThe agent service, every day can sleep two hours more is really fragrant. Their technical customer service is quite powerful, last time encountered a tricky anti-climbing problem, directly pulled a technical group to help debugging.

A final reminder for newbies:Distributed crawlers are not silver bulletsIf you have a good proxy IP and a reasonable collection strategy, you will need to use it. At first, it is recommended to use ipipgo's pay-per-use package, and then upgrade the package after figuring out the business needs, so that it is not easy to waste the silver.