Tutorial on Go

The code in this repository is part of the Programming Languages and Paradigms (PLP) Seminar at the University of Zurich.

In the Tutorial session, we will implement a simple web crawler that fetches the titles of a list of websites both synchronously and concurrently using goroutines.

Preparation

Install Go

1. Download and install Go from the official website: https://golang.org/dl/
2. Follow the installation instructions for your operating system.
3. Verify the installation by opening a terminal and running:

   go version

   You should see the installed Go version.

Set Up the Project

1. Clone this repository to your local machine:

   git clone https://github.com/vichcruz/programming-languages-tutorial.git

2. Navigate to the project directory:

   cd programming-languages-tutorial

Running the Code

1. Open a terminal and navigate to the project directory.
2. The exercise code is located in the version-0 folder. You can run it using:

   cd version-0
   go run .

3. We will progressively work on versions 1 to 4 during the tutorial.
4. The complete solution code is located in the version-5 folder. Please don't look at it yet. If you want to see the expected output of the crawler, you can run it using:

   cd version-5
   go run .

Project Structure

• main.go: The main entry point of the application.
• Fetcher.go: Contains the function to fetch the title of a webpage.
• ConcurrentCrawler.go: Implements the concurrent web crawler using goroutines.
• go.mod: Go module file specifying dependencies.

Version Differences

• version-0: Basic synchronous web crawler.
• version-1: Introduces goroutines for concurrent crawling, but without proper synchronization or result collection.
• version-2: Adds a channel to receive titles from concurrent goroutines, but has a bug in the receiving loop.
• version-3: Fixes the channel receiving logic and adds timing measurements to compare concurrent vs synchronous performance.
• version-5: Complete solution with proper concurrent crawler using sync.WaitGroup for goroutine synchronization and buffered channel for result collection.