When doing distributed crawlers, the use of proxy IP is essential. Proxy IP can help the crawler bypass the access restrictions of the target site, protect the crawler's real IP address, and improve the crawling efficiency. The following are three schemes to implement distributed crawlers through proxy IP:
Solution 1: The random IP address list is used repeatedly
In distributed crawlers, a common scheme is to implement the use of proxy IP by randomly selecting the IP list. In this scheme, each crawler process obtains a list of IP addresses from the proxy IP interface and uses these IP addresses for data crawling. When an IP fails, the crawler will re-call the API interface to obtain a new IP and continue to use it.
The advantage of this scheme is its simplicity and ease of implementation. By randomly selecting the IP list from the proxy IP interface, the alternate use of proxy IP can be easily achieved. The crawler process can continuously use the same IP list for data crawling, and when an IP is invalid, it can ensure the continuous operation of the crawler by obtaining the IP list again. This method avoids the overhead of frequent API calls and improves the efficiency of crawlers.
However, this scheme also has some disadvantages. If the number of IP addresses to be extracted is too large, the remaining IP addresses cannot be used, which reduces the availability. Due to the limited validity period of proxy IP addresses, if the demand is high and IP resources are limited, some IP addresses may not be able to bypass the access restrictions of the target site. Therefore, this solution must be properly planned and adjusted according to the actual requirements and available IP resources to ensure the continuous availability of proxy IP addresses.
Solution 2: Randomly select IP addresses and obtain them dynamically
Another common scheme in distributed crawlers is to randomly select an IP and use that IP to access the target resource. The core idea of this scheme is to obtain the proxy IP dynamically on each request to maintain the stability and anonymity of access.
The specific implementation scheme is as follows:
Each crawler process randomly selects an IP address from the proxy IP interface before making a request.
Use the selected IP address for resource access. In this way, a different IP is used for each request, which increases the possibility of anonymity and protection from detection by the target website.
If access fails or is restricted by the target website, the crawler will re-call the API interface to obtain a new IP and make the next attempt. This ensures continuous access and avoids being blocked or restricted.
While this scheme offers a high degree of flexibility and anonymity, there are some drawbacks. One of the disadvantages is the high frequency of calls to the proxy IP interface, which can put pressure on the proxy server and affect the stability of the API interface. Therefore, when selecting a proxy IP interface, it is necessary to ensure that it has sufficient reliability and stability to support high frequency calls.
In addition, schemes that randomly select IP addresses and obtain them dynamically need to take care to update the IP pool in a timely manner to ensure that the number of available proxy IP addresses is sufficient. Periodically check and clear invalid IP addresses, and add new available IP addresses to keep the IP pool updated and stable.
Solution 3: Local database storage and IP acquisition
Another common scheme in distributed crawlers is to import a large number of proxy IP into a local database and obtain available IP from the database for use. This scheme can effectively avoid frequent calls to proxy server resources and improve the stability and efficiency of distributed crawlers.
The specific implementation scheme is as follows:
Create a table in the database with fields such as IP address, port, expiration time, IP availability status, and so on. Write an import script that takes a large number of proxy IP addresses through an API interface or other means and imports them into the database.
Record the import time, expiration time, and current availability status of each IP in the database. You can use scheduled tasks or other methods to periodically update IP addresses in the database, delete expired IP addresses, and add new available IP addresses to maintain the stability of the IP address pool.
The crawler process obtains an available IP from the database and uses that IP for resource access. Each request uses a different IP, increasing anonymity and preventing the possibility of detection by the target website.
When accessing, the crawler process needs to judge the validity of the IP. If a capTCHA appears or the access fails, the crawler abandons the current IP and chooses the next available IP from the database to try.
Through the scheme of storing and obtaining IP in local database, the agent IP resources can be effectively managed and allocated, and the stability and efficiency of distributed crawler can be improved. The IP information in the database can be dynamically updated as required to keep the IP pool fresh and available.
It should be noted that Option 3 requires a certain amount of technical and resource investment in database management and maintenance. Ensuring the stability, security and timely update of the database is the key to ensure the effective operation of scheme 3. In addition, regular verification and removal of invalid IP in the database, as well as timely replenishment of new available IP, are important measures to maintain the durability and stability of scheme 3.
Through the above three schemes, the smooth progress of distributed crawlers can be achieved. Choosing the right solution depends on the specific needs and circumstances. When using proxy IP for distributed crawling, it is also necessary to pay attention to the quality and reliability of the proxy IP, and select a trusted proxy service provider, such as PublicProxyServers, to ensure the smooth operation of the crawler.