In the work of the Internet, we often face some problems: IP addresses are blocked, resulting in limited Posting and data collection, multiple accounts need to be registered but are limited to one IP account, and IP is restricted after crawling website information. These problems can be solved by using proxy IP. However, when using proxy IP, we also need to master some techniques, especially in the application of crawler proxies, the following are some effective techniques:
1. Switch the IP address before it becomes invalid
Proxy IP usually has an expiration date, especially short-acting proxy IP, which may only last a few minutes. Therefore, in order to avoid network interruption and work interruption caused by proxy IP failure, we need to make a switchover in time before proxy IP failure.
First, we need to obtain the expiration date of the proxy IP. Modern proxy IP service providers often provide API interfaces or related tools that allow users to query the remaining active time of the proxy IP. By calling these interfaces or tools regularly, we can know the expiration date of the proxy IP in time and prepare for the switch in advance.
Second, we need to set up an IP pool to store multiple available proxy IP addresses. In the process of crawler operation, the validity of proxy IP in the IP pool is constantly detected, the invalid IP is eliminated in time, and the new available proxy IP is added. In this way, when a proxy IP is about to fail, we can immediately switch to the next valid proxy IP and avoid interrupting the operation of the crawler.
In order to ensure the efficient and stable operation of the crawler, we can also take some optimization measures. For example, you can set a weight for each proxy IP address based on the historical performance of the proxy IP address, and select the proxy IP address with good performance first. At the same time, some conditions can be set to trigger the policy of automatically switching proxy IP, such as automatically switching proxy IP when continuous requests fail or timeout, so as to avoid affecting the whole crawling task because of the problem of a certain proxy IP.
In addition, considering the quality and stability of the proxy IP, it is recommended to choose a proxy IP service provider with high reputation and good reputation, and try to avoid using free proxy IP, because free proxy IP is often poor stability, easy to fail, affecting the normal operation of the crawler.
2. Control the concurrency of proxy IP addresses
Regardless of whether the proxy IP has a concurrency limit, the concurrency of the crawler proxy IP should be moderately controlled. Excessive concurrency speed will lead to extended running time and easy to be detected by the site server. Therefore, reasonable control of the concurrent IP volume can maintain the speed of the crawler program, while avoiding the access measures of the site server, and stably carry out data crawling.
3. Pay attention to the access policy
Almost every large site has an access policy, such as frequency of requests, frequency of searches, number of visits to a single IP, and so on. Some sites have stricter access policies, while others are more relaxed. Before using proxy IP for crawling, we need to study the access policy of the target site and try to avoid triggering the access restriction of the site to ensure the smooth operation of the crawler.
4. Randomize requests
For the same request, if the time interval is too regular, it is easy to be identified as a robot by the website, resulting in restricted access. In order to simulate the access behavior of real users, we can randomize the requests, adjust the request interval and request order, increase randomness, and reduce the probability of being identified as a crawler.
5, the use of high-quality proxy IP service providers
Choosing a high quality proxy IP service provider is very important. High-quality proxy IP service providers provide stable and highly anonymous proxy IP addresses, which can reduce the probability of IP blocking. Although such a service may require a fee, it is worth it for the stable operation of the crawler mission and the efficiency of the data acquisition.
Rational use of proxy IP is an important means to improve the efficiency of crawler. By switching IP in time, controlling concurrency, paying attention to access policies, randomizing requests, and selecting high-quality proxy IP service providers, we can stably crawl data, solve problems caused by IP restrictions, and improve the efficiency and accuracy of crawlers. At the same time, we should always pay attention to the changes of the Internet and flexibly adjust the proxy IP usage strategy to ensure that the crawler work continues to run efficiently.