golang crawler is too slow

With the rapid development of the Internet, a large amount of data is published on various websites, and the demand for collecting this data is getting higher and higher. In this scenario, crawler technology has become one of the important ways to collect data. As a fast and efficient programming language, golang will naturally be used to write crawler programs. However, many people have found that compared to other languages, the crawler code written in golang is significantly slower, and some crawler programs are even banned by websites. So why does the golang crawler slow down? How to make golang crawler faster? We will talk about them one by one below.

1. Unreasonable crawler program design leads to low efficiency

Although golang has a very efficient concurrent programming mechanism, if we do not make full use of goroutine when writing a crawler, or do not understand the program Optimization may lead to program inefficiency.

When many people write crawlers, they will use a single thread to crawl data on the website. This cannot fully utilize the advantages of goroutine. Secondly, the number of requests initiated by a single thread is limited, resulting in a particularly inefficient crawling of data. Low. Using goroutine, you can create multiple coroutines to crawl each data source concurrently, greatly improving concurrency efficiency. Of course, when using goroutine, we must also prevent goroutine leakage and the overhead caused by goroutine scheduling.

2. The proxy IP is unstable

When crawling data, we often encounter situations where an IP frequently visits the same website, which will cause the IP to be blocked. In order to avoid such a situation, we usually use proxy IP for access. However, if the proxy IP we use is unstable, the crawler speed will often slow down because the proxy IP is unavailable.

For this problem, we can solve it in the following ways:

1. Use stable proxy IP resources.

When choosing proxy IP resources, try to choose services provided by reliable proxy IP vendors. Because these manufacturers generally conduct quality control and management of proxy IP to ensure the stability and reliability of their proxy IP resources.

2. Periodically detect the proxy IP

Among the selected proxy IP resources, try to select IP addresses with high stability, or perform periodic detection of the proxy IP and eliminate them in time Unstable proxy IP address to ensure the normal operation of our crawler program.

3. The crawler code is not efficient enough

In addition to the above two reasons, the efficiency of the code itself is also one of the important reasons that affects the speed of the crawler.

When we write a crawler program, we must reduce the amount of calculations in the code as much as possible and improve the execution efficiency of the code to increase the speed of the crawler program. For example, using array-based data structures, using fully tested regular expressions, etc. can greatly improve the execution speed of the program.

4. The capabilities of the crawler program are limited

The requests we initiate may not necessarily receive a response. Sometimes, we cannot access certain servers, or the servers restrict our access. When we are throttled, our crawler speed becomes slower.

How to improve the crawler's capabilities? In addition to using a stable proxy IP mentioned above, you can also use the following methods:

1. Try to introduce cookie/session information to enhance the capabilities of the crawler and bypass the server's firewall.

2. Control the request frequency and crawling depth, and reduce the risk of being blocked through reasonable crawling rules.

When writing a crawler, the most important thing is to try to understand the anti-crawling mechanism of the target site so as to better optimize our crawler program.

After completing the above optimization, I believe your golang crawler program will become faster and more stable, bringing a more efficient data collection experience.

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