Book Image

Go Web Scraping Quick Start Guide

By : Vincent Smith
Book Image

Go Web Scraping Quick Start Guide

By: Vincent Smith

Overview of this book

Web scraping is the process of extracting information from the web using various tools that perform scraping and crawling. Go is emerging as the language of choice for scraping using a variety of libraries. This book will quickly explain to you, how to scrape data data from various websites using Go libraries such as Colly and Goquery. The book starts with an introduction to the use cases of building a web scraper and the main features of the Go programming language, along with setting up a Go environment. It then moves on to HTTP requests and responses and talks about how Go handles them. You will also learn about a number of basic web scraping etiquettes. You will be taught how to navigate through a website, using a breadth-first and then a depth-first search, as well as find and follow links. You will get to know about the ways to track history in order to avoid loops and to protect your web scraper using proxies. Finally the book will cover the Go concurrency model, and how to run scrapers in parallel, along with large-scale distributed web scraping.
Table of Contents (10 chapters)

The Go concurrency model

As you have seen, many of the problems with concurrent programs stem from sharing memory resources between multiple threads. This shared memory is used to communicate state and can be very fragile, with great care needed to ensure that everything stays up and running. In Go, concurrency is approached with the mantra:

Do not communicate by sharing memory; instead, share memory by communicating.

When you use mutexes and locks around a common object, you are communicating by sharing memory. Multiple threads look to the same memory location to alert and to provide information for the other threads to use. Instead of doing this, Go provides tools to help share memory by communicating.

Goroutines

Up until...