Goroutines & Concurrency Basics

🐹 Go Language Lesson 13 Advanced

Concurrency is built directly into the core design of Go. Goroutines are lightweight threads managed by the Go runtime, rather than the host operating system.

1 Goroutines vs. OS Threads (The `go` Keyword)

While standard OS threads require megabytes of stack memory, a **Goroutine** starts with just a few kilobytes. To launch a function concurrently as a goroutine, simply prepend the statement with the **`go`** keyword: `go doWork()`. The scheduler multiplexes thousands of goroutines onto a small number of physical OS threads automatically.

2 Goroutines Code

Let's run a program that launches functions concurrently using goroutines:

Go — Goroutines ▶ Run Code

package main

import (
    "fmt"
    "time"
)

func showMessage(msg string) {
    for i := 1; i <= 3; i++ {
        fmt.Println(msg)
        time.Sleep(100 * time.Millisecond) // Yield execution thread
    }
}

func main() {
    // Launch function concurrently as a Goroutine
    go showMessage("Async Work Running!")

    // Main thread execution
    showMessage("Main thread running!")

    // Wait slightly to let the async goroutine finish before main exits
    time.Sleep(150 * time.Millisecond)
}

3 Code Challenge

Challenge: Write a program that launches two goroutines. Each goroutine should print a unique counting sequence (e.g. one prints numbers 1-5, and the other prints letters A-E), sleeping for 50 milliseconds between prints.