What are goroutines?

Lightweight execution threads managed by the Go runtime. They are created with the go keyword before a function call.

Main characteristics:

• Lower memory consumption: A goroutine starts with a small stack size (usually 2 KB), which can dynamically grow or shrink.
• Faster creation: Creating a goroutine is much faster than creating a system thread.
• Multiplexing onto system threads: Multiple goroutines can be multiplexed onto fewer system threads by the Go runtime scheduler.
• Cooperative scheduling: Goroutines are not preemptively interrupted; they voluntarily yield control to the scheduler (e.g., during blocking calls or explicit calls to runtime.Gosched()).

Example of creation:

package main

import (
	"fmt"
	"time"
)

func sayHello() {
	fmt.Println("Hello from goroutine!")
}

func main() {
	go sayHello() // Launch sayHello as a goroutine
	fmt.Println("Hello from main function!")
	time.Sleep(1 * time.Second) // To prevent the main function from finishing before the goroutine
}

Comparison with threads:

Attribute	Go Goroutines	OS Threads
Management	Go runtime environment	Operating system
Memory usage	Low, dynamic stack	High, fixed stack
Creation	Fast	Slow
Scheduling	Cooperative	Preemptive
Synchronization	Channels, sync package	Mutexes, OS semaphores